The Indeclinable Possessives jeho, její, jejich | Czech Grammar

Czech possessives are famous for agreeing with the thing possessed — můj dům, mého domu, mému domu all change shape. So the third-person possessives come as a relief and a shock at the same time: two of them, jeho ("his/its") and jejich ("their"), never change at all, while the third, její ("her"), declines fully. This split — two frozen words and one that inflects — is one of those rare corners of Czech grammar that is easier than you expect for two of the three, and a trap precisely because of the odd one out. This page nails down which is which.

The asymmetry in one table

The whole story fits in a single comparison. His and their are stones; her is liquid.

Possessive	Behavior
jeho (his / its)	indeclinable — one frozen form
jejich (their)	indeclinable — one frozen form
její (her)	declines like a soft adjective

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Two of the three third-person possessives are gifts: jeho and jejich never inflect, ever. Whatever case or gender the noun is in, you write the same word. The only one you have to decline is její ("her").

jeho never moves

Take jeho and march it through the cases with different nouns. The noun around it changes; jeho sits perfectly still:

Case	Phrase	English
nom.	jeho dům	his house
dat.	jeho ženě	to his wife
loc.	o jeho práci	about his work
gen./pl.	jeho auta	his cars / of his car
dat. pl.	jeho přátelům	to his friends

To je jeho dům a tamhle bydlí jeho rodiče.

That's his house and his parents live over there.

Celý večer jsme mluvili o jeho práci.

We talked about his work all evening.

Dej to jeho bratrovi, ne mně.

Give it to his brother, not to me.

In o jeho práci the noun is locative and in jeho bratrovi it's dative — but jeho doesn't budge. The same is true of jejich ("their"): one shape for every slot.

Jejich děti chodí do stejné školy jako naše.

Their children go to the same school as ours.

Byli jsme včera u jejich babičky na obědě.

We were at their grandmother's for lunch yesterday.

její declines — like a soft adjective

Now the exception. její ("her") behaves like a normal soft adjective (the jarní type): it grows endings to agree with the noun. In front of a feminine noun it happens to stay její throughout (soft feminine adjectives are invariant in the singular), which lulls learners into thinking it never changes — but the masculine and neuter forms give it away.

Case	"his" (frozen)	"her" (declines)
nom.	jeho dům	její dům
gen.	jeho domu	jejího domu
dat.	jeho domu	jejímu domu
loc.	(o) jeho domě	(o) jejím domě
instr.	(s) jeho domem	(s) jejím domem

Put the two columns side by side and the asymmetry is undeniable: jeho repeats one word five times, while her runs její → jejího → jejímu → jejím → jejím.

Znám jejího bratra i jejího otce.

I know her brother and her father.

Půjčil jsem to jejímu kamarádovi.

I lent it to her friend.

Bydlí v jejím novém bytě.

He lives in her new flat.

Before a feminine noun, though, její really does sit still — její kniha, její knihy, její knize — because that's where the soft-adjective endings collapse. So "I know her sister" is Znám její sestru, but "I know her brother" is Znám jejího bratra. The masculine pulls the ending out of hiding.

The jejich vs jejích trap

Watch the diacritic. jejich (short i, no accent) means "their" and never declines. jejích (long í, with the accent) is the genitive/locative plural of její — "of her" things. They differ by a single háček and a length, and they mean completely different people.

To jsou jejich knihy.

Those are their books. (jejich = belonging to them)

Polovina jejích knih je o historii.

Half of her books are about history. (jejích = genitive plural of 'her')

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One háček changes the owner. jejich = "their" (frozen); jejích = "of her" (the long-vowel genitive/locative plural of její). When you mean "their," there is no accent and the word never changes.

jeho / její / jejich vs the reflexive svůj

There is one more thing these possessives share, and it's the source of the most common error of all. Jeho, její, and jejich always point to someone other than the subject. When the owner is the subject of the clause, Czech switches to the reflexive svůj ("one's own").

Petr myje *své auto. — Petr washes *his own car.
Petr myje *jeho auto. — Petr washes *his car (someone else's — another man's).

English has no way to mark this; "his car" is ambiguous about whose. Czech forces the choice every time, and choosing jeho when you mean the subject's own thing is a real change of meaning, not a stylistic slip.

Petr prodal své auto, ne jeho auto.

Peter sold his own car, not his (= another man's) car.

Vzala si svůj kabát a odešla.

She took her own coat and left.

For the full reflexive picture see svůj overview and the dedicated svůj vs jeho page.

Common Mistakes

❌ Dej to jehému bratrovi.

Incorrect — jeho is indeclinable; there is no such form as 'jehému.' Just jeho bratrovi.

✅ Dej to jeho bratrovi.

Give it to his brother.

❌ Znám její bratra.

Incorrect — before a masculine animate noun její must decline: jejího bratra.

✅ Znám jejího bratra.

I know her brother.

❌ Mluvil jsem s její otcem.

Incorrect — the instrumental/dative needs the inflected form: s jejím otcem.

✅ Mluvil jsem s jejím otcem.

I spoke with her father.

❌ To jsou jejích auta.

Wrong word for 'their cars' — 'their' is jejich (no accent); jejích means 'of her.'

✅ To jsou jejich auta.

Those are their cars.

❌ Petr umyl jeho auto.

Wrong reference if you mean his own car — for the subject's own car use the reflexive: Petr umyl své auto. As written, jeho means someone else's.

✅ Petr umyl své auto.

Peter washed his own car.

Key Takeaways

jeho ("his/its") and jejich ("their") are completely indeclinable — one frozen form across every case, gender, and number.
její ("her") declines like a soft adjective: její, jejího, jejímu, jejím — though before a feminine noun it stays její, the masculine/neuter forms expose the inflection.
Don't invent forms of jeho (jehému ✗), and don't freeze její where it must inflect (její bratra ✗ → jejího bratra).
Mind the diacritic: jejich = "their"; jejích = "of her" (gen./loc. pl. of její).
jeho / její / jejich mean someone else's; for the subject's own thing use the reflexive svůj.

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