In English, "my" is a single frozen word: my house, my coffee, my children — "my" never changes. Polish possessives work on a completely different principle. mój ("my"), twój ("your," singular), nasz ("our"), and wasz ("your," plural) are not fixed words but adjective-like forms that agree with the thing possessed — its gender, its number, and its case. The owner is irrelevant to the form; what matters is what is owned. Once you accept that, the whole system is just regular adjective agreement, and you already use that everywhere else in Polish.
Agreement with the possessed noun
"My" changes shape depending on the gender of the noun after it. The four basic singular forms of mój are:
| Gender of the owned noun | Form of "my" | Example |
|---|---|---|
| masculine | mój | mój dom (my house) |
| feminine | moja | moja kawa (my coffee) |
| neuter | moje | moje dziecko (my child) |
| masculine-personal plural | moi | moi synowie (my sons) |
| non-masc-personal plural | moje | moje koty (my cats) |
To jest mój dom, a tam stoi moja córka.
This is my house, and over there stands my daughter. (mój dom — m; moja córka — f)
Moje dziecko już śpi.
My child is already asleep. (neuter → moje)
Moi rodzice mieszkają na wsi.
My parents live in the countryside. (masc-personal plural → moi)
The crucial mental shift: in mój samochód but moja książka, the "my" changed not because I changed but because samochód (car, masculine) and książka (book, feminine) differ in gender. twój, nasz, and wasz behave identically — twój dom, twoja kawa, twoje dziecko, twoi synowie; nasz dom, nasza kawa, nasze dziecko, nasi synowie.
Gdzie jest twoja siostra? Twój brat jej szuka.
Where is your sister? Your brother is looking for her. (twoja — f; twój — m)
Nasi sąsiedzi są bardzo mili.
Our neighbours are very nice. (masc-personal plural → nasi)
They also decline for case
Agreement is not only about gender and number — mój and friends carry case too, just like any adjective. So beyond the five nominative forms above, mój takes a different shape in each of the seven cases. Here is mój fully declined in the singular and plural:
| Case | Masculine | Feminine | Neuter | Masc-pers. pl. | Other pl. |
|---|---|---|---|---|---|
| Nominative | mój | moja | moje | moi | moje |
| Genitive | mojego | mojej | mojego | moich | moich |
| Dative | mojemu | mojej | mojemu | moim | moim |
| Accusative | mój / mojego* | moją | moje | moich | moje |
| Instrumental | moim | moją | moim | moimi | moimi |
| Locative | moim | mojej | moim | moich | moich |
The masculine accusative is *mój for inanimate nouns (widzę mój dom) but mojego for animate ones, following the animacy rule: widzę mojego brata ("I see my brother").
Idę z moim bratem na mecz.
I'm going to the match with my brother. (instrumental → moim)
Opowiedziałam jej o mojej siostrze.
I told her about my sister. (locative → o mojej siostrze)
Widzę mojego brata na przystanku.
I see my brother at the bus stop. (animate accusative → mojego)
So "my" is not one word but a small paradigm. The same case endings appear on twój, nasz, wasz (e.g. twojego, naszego, waszej; z twoim ojcem, w naszej szkole). They are all built like soft adjectives, which is why if you know adjective declension you already half-know these.
Full and contracted forms
For mój and twój there is a high-frequency contracted variant in the oblique cases: alongside mojego / mojemu / mojej / moich you will hear and read mego / memu / mej / mych (and likewise twego, twemu, twej, twych). The contracted forms are shorter and feel slightly more (literary) or elevated; the full forms are the everyday default.
| Full (everyday) | Contracted (literary) | |
|---|---|---|
| genitive m./n. | mojego | mego |
| dative m./n. | mojemu | memu |
| gen./dat./loc. f. | mojej | mej |
Nie widziałem mego ojca od lat.
I haven't seen my father for years. (contracted mego — slightly literary)
Nie widziałem mojego ojca od lat.
I haven't seen my father for years. (everyday mojego — same meaning)
For nasz and wasz there is no such contraction; they only have the full forms (naszego, naszemu, naszej, naszych).
Common Mistakes
❌ Mój książka jest na stole.
Incorrect — książka is feminine, so 'my' must agree: moja.
✅ Moja książka jest na stole.
My book is on the table.
The classic A1 error: leaving mój in its dictionary (masculine) form regardless of the noun. "My" must take the gender of what is owned — moja książka, not mój książka.
❌ Widzę mój brata.
Incorrect — brat is animate, so the accusative is mojego, with the genitive-style ending.
✅ Widzę mojego brata.
I see my brother.
Animate masculine nouns take a genitive-shaped accusative, and the possessive follows: mojego brata, not mój brata.
❌ Rozmawiam z mój ojcem.
Incorrect — the instrumental needs moim to match ojcem.
✅ Rozmawiam z moim ojcem.
I'm talking with my father.
After a preposition that takes the instrumental (z), the possessive must also be instrumental: z moim ojcem. Leaving mój uninflected is the most common case error here.
❌ Moje synowie studiują w Warszawie.
Incorrect — sons are male humans, so the masculine-personal plural is moi.
✅ Moi synowie studiują w Warszawie.
My sons study in Warsaw.
The masculine-personal plural takes the special form moi (also twoi, nasi, wasi), not moje. Reserve moi/twoi/nasi/wasi for groups with male humans.
Key Takeaways
- mój, twój, nasz, wasz agree with the possessed noun — its gender, number, and case — not with the owner.
- Basic forms: mój (m), moja (f), moje (n), moi (masc-pers. pl.), moje (other pl.); twój, nasz, wasz follow the same pattern.
- They fully decline for all seven cases (mojego, mojemu, moim, mojej, moją…), exactly like adjectives.
- Watch the animate accusative: widzę mojego brata, not mój brata.
- The contracted mego / mej / mych (only for mój, twój) is literary; produce the full forms and just recognise the short ones.
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Start learning Polish→Related Topics
- Grammatical Gender: Three GendersA1 — Every Polish noun is masculine, feminine, or neuter — and its gender, usually readable from the nominative ending, drives all agreement.
- Adjective Agreement: Gender, Number, CaseA1 — Polish adjectives agree with their noun in gender, number, and case all at once — so a single 'good' has half a dozen forms.
- His, Her, Their: jego, jej, ich (Invariable)A2 — Unlike mój and nasz, the third-person possessives jego, jej and ich never change form — they are frozen genitive pronouns that ignore the gender and case of the noun.
- swój: The Reflexive PossessiveB1 — When the owner is the subject of the clause, Polish forces the reflexive possessive swój — and using jego or jej instead quietly changes the meaning to 'someone else's'.
- Full Adjective Declension TablesA2 — The complete adjective paradigm across all seven cases and both numbers — and why it's the most regular, learnable part of the Polish case system.