Relative Pronouns: koji and što | Croatian Grammar

The relative pronoun koji / koja / koje ("who, which, that") is how Croatian joins a clause onto a noun: čovjek koji radi ("the man who works"), knjiga koju čitam ("the book that I'm reading"). It looks like one word, but it carries two pieces of grammatical information at once, and they come from two different places. Its gender and number come from outside the relative clause — from the noun it points back to (the antecedent). Its case comes from inside the relative clause — from the job it does there. This dual-source agreement is the single most important thing to master about Croatian relatives, and English, with its invariant "who / which / that", never asks you to think about it.

The core principle: gender and number from outside, case from inside

Take one antecedent — čovjek ("man", masculine singular) — and watch koji change case as its role inside the relative clause changes, while staying masculine singular throughout because that is what čovjek is.

Role inside the clause	Form	Example
Subject (nominative)	koji	čovjek koji radi (the man who works)
Direct object (accusative)	kojeg(a)	čovjek kojeg vidim (the man whom I see)
Indirect object (dative)	kojem(u)	čovjek kojem dajem (the man to whom I give)
After a preposition (instr.)	kojim	čovjek s kojim radim (the man I work with)
Possessor (genitive)	kojeg(a)	čovjek kojeg se sjećam (the man I remember)

Every one of these is masculine singular — because čovjek is — but the ending shifts with the relative pronoun's job: nominative subject koji, accusative object kojeg, dative recipient kojem, instrumental complement kojim. The antecedent fixes the gender/number; the inner clause fixes the case. Train yourself to ask two separate questions: what is the antecedent? (gender + number) and what does the relative pronoun do in its own clause? (case).

To je kolega koji mi je pomogao.

That's the colleague who helped me. — 'koji' nominative: it is the subject of 'pomogao'.

To je kolega kojeg sam jučer upoznao.

That's the colleague whom I met yesterday. — 'kojeg' accusative: object of 'upoznao'.

To je kolega kojem vjerujem.

That's the colleague I trust. — 'kojem' dative: 'vjerovati' takes the dative.

To je kolega s kojim dijelim ured.

That's the colleague I share an office with. — 'kojim' instrumental after 's'.

The agreement flips with the antecedent

Change the antecedent and the gender/number of koji changes with it — but the case still answers to the inner clause. Here the antecedent is feminine, then plural.

Žena koja sjedi tamo je moja teta.

The woman who's sitting there is my aunt. — 'koja' feminine nominative (subject of 'sjedi').

Žena koju si pozdravio je moja teta.

The woman you greeted is my aunt. — 'koju' feminine accusative (object of 'pozdravio').

Studenti koji su prošli ispit slave.

The students who passed the exam are celebrating. — 'koji' masculine plural nominative.

Studenti koje sam učio sad rade.

The students whom I taught are now working. — 'koje' masculine plural accusative.

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Two questions, two answers. Gender and number? Look back at the noun (the antecedent). Case? Look inside the relative clause and ask what the pronoun is doing there — subject, object, recipient, object of a preposition. Get into the habit of answering them separately and koji stops being hard.

Prepositions sit before koji — never stranded

As everywhere in Croatian, a preposition that governs the relative pronoun stands before it, inside the relative clause. English drops the preposition to the end ("the town I live in"); Croatian keeps it attached to koji ("the town in which I live"). This is not a formal or bookish option as it is in English — it is the only grammatical order.

Grad u kojem živim je malen.

The town I live in is small. — 'u kojem' (locative); never *koji živim u.

Auto kojim se vozimo je njegov.

The car we're driving is his. — 'kojim' instrumental, no preposition needed here ('voziti se').

Prijatelj o kojem ti pričam stiže sutra.

The friend I'm telling you about arrives tomorrow. — 'o kojem' (locative), preposition first.

Stol za kojim sjedimo je rezerviran.

The table we're sitting at is reserved. — 'za kojim' (instrumental), preposition fronted.

kojeg vs koga: the masculine accusative, and the length variants

The masculine singular relative pronoun has two things worth a closer look. First, like all pronominal forms it obeys animacy in the accusative: with an animate antecedent the accusative copies the genitive (kojeg), and with an inanimate antecedent it copies the nominative (koji). So čovjek kojeg vidim ("the man I see", animate) but stol koji vidim ("the table I see", inanimate). Second, the genitive/accusative form has a short and a long variant, kojeg ↔ kojega, and the dative/locative likewise kojem ↔ kojemu; both are correct, with the longer forms reading slightly more formal — the same length switch you meet on adjectives and demonstratives (see demonstrative declension).

Pas kojeg smo udomili je sad miran.

The dog we adopted is calm now. — animate antecedent → accusative 'kojeg' (= genitive).

Stol koji smo kupili premalen je.

The table we bought is too small. — inanimate antecedent → accusative 'koji' (= nominative).

To je profesor kojega svi cijene.

That's the professor everyone respects. — the longer 'kojega', a touch more formal than 'kojeg'.

The invariable relative što

Alongside koji there is a second relative, što, which is invariable — it never changes form. It is used in two main situations:

After a quantifier or neuter "everything" word — sve što, ono što, nešto što — meaning "all/that which".
As a sentential relative referring back to a whole clause, not a single noun: "..., which surprised me."

In everyday speech, što is also a common colloquial stand-in for koji with simple, often inanimate, antecedents — but when što refers to a person and the relative needs an oblique case, a resumptive pronoun is added (čovjek što ga vidim — "the man that I see him"). For clean writing, use koji whenever a case other than the nominative is required for a personal or specific antecedent; this choice is laid out in detail on the koji vs što page.

Sve što imam je tvoje.

Everything I have is yours. — invariable 'što' after 'sve'.

Reci mi ono što znaš.

Tell me what you know. — 'ono što' = 'that which'.

Zakasnio je na vlak, što me nije iznenadilo.

He missed the train, which didn't surprise me. — sentential 'što' refers to the whole previous clause.

čiji — the relative "whose"

To express "whose" inside a relative clause, Croatian uses čiji / čija / čije. Like koji it has a dual source — but with a twist: it agrees in gender/number/case with the possessed thing (the noun right after it), while pointing back to the possessor as its antecedent.

Susjed čiji pas laje cijelu noć se odselio.

The neighbour whose dog barks all night has moved away. — 'čiji' agrees with masculine 'pas'.

To je spisateljica čije knjige obožavam.

That's the writer whose books I adore. — 'čije' agrees with the possessed 'knjige' (acc. plural).

The comma: a logic comma, not a habit

Croatian punctuates relative clauses by meaning, not by a fixed rule. A non-restrictive relative — extra, parenthetical information that could be dropped without changing which thing you mean — is set off with a comma. A restrictive relative — one that picks out which thing you mean — is generally not preceded by a comma. This is the opposite habit from learners who comma every koji automatically.

Moj brat, koji živi u Splitu, dolazi sutra.

My brother, who lives in Split, is coming tomorrow. — non-restrictive (I have one brother): commas.

Susjed koji živi iznad nas je vrlo glasan.

The neighbour who lives above us is very loud. — restrictive (specifies which neighbour): no comma.

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Ask whether the relative clause is telling you which one (restrictive — no comma) or just adding a side remark about an already-identified thing (non-restrictive — commas). Moj brat, koji… assumes one brother and adds a remark; brat koji… singles out which brother.

Common mistakes

❌ Žena koji sjedi tamo je moja teta.

Incorrect — the antecedent 'žena' is feminine, so the relative must be 'koja', not masculine 'koji'.

✅ Žena koja sjedi tamo je moja teta.

The woman sitting there is my aunt. — feminine 'koja'.

❌ Čovjek koji vidim je moj profesor.

Incorrect — the pronoun is the OBJECT of 'vidim', so it needs the accusative 'kojeg', not nominative 'koji'.

✅ Čovjek kojeg vidim je moj profesor.

The man I see is my professor. — accusative 'kojeg' (case from inside the clause).

❌ Grad koji živim u je malen.

Incorrect — the preposition can't be stranded; it goes before 'koji': 'u kojem'.

✅ Grad u kojem živim je malen.

The town I live in is small. — 'u kojem', preposition fronted.

❌ Kolega kojeg vjerujem je pošten.

Incorrect — 'vjerovati' takes the dative, so the relative is 'kojem', not the accusative 'kojeg'.

✅ Kolega kojem vjerujem je pošten.

The colleague I trust is honest. — dative 'kojem' (verb governs the case).

❌ Spisateljica čiju knjige obožavam.

Incorrect — 'čiji' agrees with the possessed noun; 'knjige' is plural, so it's 'čije'.

✅ Spisateljica čije knjige obožavam.

The writer whose books I adore. — 'čije' agrees with 'knjige'.

Key takeaways

koji takes its gender and number from the antecedent (outside) but its case from its role inside the relative clause — answer those two questions separately.
Subject → koji, object → kojeg(a), recipient → kojem(u), after a preposition → the case that preposition governs (s kojim, u kojem, o kojem).
Prepositions stand before koji, never stranded at the end.
Invariable što covers sve što / ono što and whole-clause ("which …") antecedents; prefer koji for personal or oblique-case antecedents in careful writing.
čiji ("whose") agrees with the possessed noun; the comma marks a non-restrictive (parenthetical) relative, not every relative.

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