Relative Clauses in Depth | Croatian Grammar

A relative clause is a clause that modifies a noun — the who-part of the woman who called, the which-part of the city which I love. English does this with a small set of invariable words (who, which, that) and is happy to leave the preposition dangling at the end (the town I live in). Croatian does neither. Its main relativiser, koji, is fully inflected, and any preposition that governs it must travel with it to the front of the clause. This page shows you exactly how relative clauses are assembled, when to reach for što or čiji instead, and how the comma sorts essential from extra information.

koji: gender and number from the antecedent, case from inside the clause

The single most important fact about koji / koja / koje is that it carries two pieces of information drawn from two different places. Its gender and number come from the noun it points back to — the antecedent, which sits outside the relative clause. Its case, however, is decided entirely by the job it does inside its own clause. The antecedent tells you the gender and number; the inner verb or preposition tells you the case.

Watch the same feminine antecedent žena keep koji feminine singular throughout, while the ending shifts with the pronoun's role:

Role inside the relative clause	Form (fem. sg.)	Example
Subject (nominative)	koja	žena koja zove (the woman who is calling)
Direct object (accusative)	koju	žena koju volim (the woman I love)
Recipient (dative)	kojoj	žena kojoj vjerujem (the woman I trust)
After a preposition (locative)	kojoj	žena o kojoj pričam (the woman I'm talking about)
Possessor (genitive)	koje	žena koje se sjećam (the woman I remember)

So whenever you build a relative clause, train yourself to ask two separate questions: what is the antecedent? (that fixes gender and number) and what does the relative pronoun do in its own clause? (that fixes the case). The full paradigm and the kojeg/koga animacy detail live on the relative pronoun koji page; here we focus on building whole clauses.

Žena koju volim živi u Rijeci.

The woman I love lives in Rijeka. — 'koju' is feminine (from 'žena') but accusative, because it's the object of 'volim'.

Ovo je grad koji obožavam.

This is the city I adore. — 'koji' masculine accusative; inanimate, so the accusative looks like the nominative.

Kolegica kojoj sam posudio knjigu vraća je sutra.

The colleague I lent the book to is returning it tomorrow. — 'kojoj' dative, because the relative is the recipient.

Prepositions are pied-piped — never stranded

When the relative pronoun is governed by a preposition, that preposition stands before koji, inside the relative clause. This is not the formal-register option it is in English (the city in which I live); in Croatian it is the only grammatical order. There is no version of the sentence where the preposition sits at the end.

Grad u kojem živim je malen.

The city I live in is small. — 'u kojem' (locative); you can never say *grad koji živim u.

Prijatelj s kojim putujem kasni.

The friend I'm travelling with is running late. — 's kojim' (instrumental), preposition fronted.

To je tema o kojoj svi pričaju.

That's the topic everyone's talking about. — 'o kojoj' (locative); the preposition leads, not trails.

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For English speakers the reflex to break is preposition-stranding. Before writing a relative clause, find the preposition the verb needs (pričati o → "talk about", putovati s → "travel with") and put it in front of koji. The English word order "...I'm talking about" must be rebuilt as "...about which I'm talking".

The invariable relative što

Alongside koji there is a second relativiser, što, which never changes form. Standard Croatian uses it in two clear roles, plus a colloquial third:

Sentential relative — što refers back to a whole clause, not a single noun, where English uses which: ..., which surprised me.
After neuter quantifier words — sve što ("everything that"), ono što ("that which"), nešto što ("something that").
Colloquially, as an all-purpose stand-in for koji with simple antecedents — fine in speech, but in careful writing prefer koji whenever a non-nominative case is needed, especially for people.

Zakasnio je na sastanak, što me nije iznenadilo.

He was late for the meeting, which didn't surprise me. — sentential 'što' points back to the whole first clause.

Sve što imam dugujem svojim roditeljima.

Everything I have I owe to my parents. — invariable 'što' after the quantifier 'sve'.

Reci mi ono što stvarno misliš.

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

There is also a purely colloquial pattern worth recognising (and avoiding in writing): speech often relativises with invariable što and then plugs the case back in with a resumptive clitic pronoun further along — čovjek *što sam ga vidio*, literally "the man that I saw him." Because što never inflects, the ga carries the accusative that kojeg would have carried, so the slot is filled twice. It is common and natural in casual speech, but nonstandard; in careful Croatian use the inflected koji (čovjek kojeg sam vidio) and drop the resumptive pronoun.

Ono je dečko što sam ti ga spominjala.

That's the guy (that) I mentioned to you. — colloquial 'što… ga' resumptive: invariable 'što' plus the clitic 'ga' refilling the accusative; careful writing prefers 'kojeg sam ti spominjala'.

The full division of labour between the two is on the koji vs što page.

čiji — the relative "whose"

To say "whose" inside a relative clause, Croatian uses čiji / čija / čije. It works like a possessive adjective: it agrees in gender, number and case with the thing possessed (the noun right after it), while pointing back to the possessor as its antecedent. So in čovjek čiji sin studira ("the man whose son is studying"), čiji is masculine because sin is masculine — not because čovjek is.

Čovjek čiji sin studira u Zagrebu vrlo je ponosan.

The man whose son is studying in Zagreb is very proud. — 'čiji' agrees with masculine 'sin'.

To je spisateljica čije knjige svi čitaju.

That's the writer whose books everyone reads. — 'čije' agrees with the possessed plural 'knjige'.

Susjedi čiju mačku čuvamo na godišnjem su.

The neighbours whose cat we're looking after are on holiday. — 'čiju' is feminine accusative, agreeing with 'mačku' (the cat we're keeping).

Restrictive vs non-restrictive: the comma carries meaning

Croatian punctuates relative clauses by sense, not by a mechanical rule. The question is whether the clause is restrictive — it tells you which thing is meant, and the sentence collapses without it — or non-restrictive — it adds a parenthetical remark about something already identified, and could be dropped.

A restrictive relative takes no comma: it is read in one continuous breath with its antecedent. A non-restrictive relative is set off by commas (one before, and one after if the sentence continues), marking the pause and the side-remark status.

Type	Comma?	Example
Restrictive (identifies which)	No comma	Studenti koji su položili slave. (The students who passed are celebrating.)
Non-restrictive (extra remark)	Commas	Moja sestra, koja živi u Splitu, dolazi. (My sister, who lives in Split, is coming.)

Ljudi koji rano ustaju obično su produktivniji.

People who get up early are usually more productive. — restrictive, NO comma; it specifies which people.

Moja sestra, koja živi u Splitu, dolazi za vikend.

My sister, who lives in Split, is coming this weekend. — non-restrictive, set off by commas; I have one sister, the clause just adds information.

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Ask: does the relative clause tell me which one, or just add a side note about something already pinned down? Brat koji živi u Splitu singles out one brother among several (no comma); moj brat, koji živi u Splitu assumes a single brother and tacks on a remark (commas). The comma is a meaning signal, not a habit.

Common Mistakes

❌ Žena koji volim živi u Rijeci.

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

✅ Žena koju volim živi u Rijeci.

The woman I love lives in Rijeka. — feminine accusative 'koju'.

❌ Grad koji živim u je malen.

Incorrect — the preposition 'u' cannot be stranded at the end; it goes before the pronoun: 'u kojem'.

✅ Grad u kojem živim je malen.

The city I live in is small. — pied-piped 'u kojem'.

❌ Kolegica koju vjerujem je poštena.

Incorrect — 'vjerovati' takes the dative, so the relative is 'kojoj', not the accusative 'koju'.

✅ Kolegica kojoj vjerujem je poštena.

The colleague I trust is honest. — dative 'kojoj', because the verb governs the dative.

❌ Spisateljica čiju knjige svi čitaju.

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

✅ Spisateljica čije knjige svi čitaju.

The writer whose books everyone reads. — 'čije' agrees with 'knjige'.

❌ Ljudi, koji rano ustaju, produktivniji su.

Incorrect — a restrictive relative (it specifies which people) takes NO commas.

✅ Ljudi koji rano ustaju produktivniji su.

People who get up early are more productive. — restrictive, no commas.

Key Takeaways

koji takes gender and number from the antecedent (outside the clause) but its case from its own role inside the clause — answer those two questions separately.
Subject → koji, object → koju/kojeg, recipient → kojoj/kojem, after a preposition → the case that preposition governs.
Prepositions are pied-piped in front of koji (u kojem, s kojim, o kojoj) — never stranded at the end as in English.
što is invariable: use it for whole-clause antecedents (..., što me iznenadilo) and after sve / ono / nešto; prefer koji for people and oblique cases in writing.
čiji ("whose") agrees with the possessed noun; the comma distinguishes a non-restrictive (parenthetical, commas) from a restrictive (essential, no comma) relative.

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