bát se — to be afraid | Czech Grammar

Bát se ("to be afraid, to fear") is a small word with two outsized difficulties. First, the stem shifts: the infinitive is bá-, but the present runs on boj-, so bojím se looks nothing like bát se. Second, and more important for getting sentences right, bát se governs the genitive — you are afraid of something, and that something changes its ending. On top of that, the reflexive se must sit in the sentence's second position. This page handles all three.

The present tense: boj-

The infinitive bát loses its bá- shape entirely in the present, which is built on boj- with the -í- endings. The reflexive se travels along with every form.

Person	Form	Meaning
já	bojím se	I'm afraid
ty	bojíš se	you're afraid (sg.)
on / ona / ono	bojí se	he / she / it is afraid
my	bojíme se	we're afraid
vy	bojíte se	you're afraid (pl./formal)
oni / ony	bojí se	they're afraid

💡

Store the alternation as a fact, not a derivation: infinitive bá- (bát se, budu se bát), present boj- (bojím se). You cannot reach bojím by ear from bát. The same kind of jump shows up in smát se → sm ěju se.

The key point: bát se takes the genitive

In English "afraid" is followed by "of." In Czech there is no preposition — instead, the thing feared goes straight into the genitive case. This is the single most important thing to learn about the verb.

Bojím se psa, je obrovský.

I'm afraid of the dog, it's huge.

Nebojíš se tmy?

Aren't you afraid of the dark?

Jako dítě jsem se hrozně bála bouřky.

As a child I was terribly afraid of thunderstorms. (female speaker)

In these, pes → psa, tma → tmy, and bouřka → bouřky are all genitive. An English speaker's instinct is to leave the noun in its dictionary (nominative) form or to reach for a preposition; resist both. The fear simply pulls the noun into the genitive.

You can also fear a whole situation, expressed as a že-clause:

Bojím se, že to nestihneme.

I'm afraid we won't make it in time.

And you can be afraid to do something, with a plain infinitive:

Děti se bály jít samy do sklepa.

The children were afraid to go down to the cellar by themselves.

A second pattern: bát se o + accusative

There is a related but distinct construction. While bát se + genitive means "to be afraid of" (the thing is a threat), bát se o + accusative means "to fear for, to be worried about" (you fear something might happen to what you love).

Bojím se o tebe, zavolej mi, až dorazíš.

I'm worried about you, call me when you get there.

Celou zimu se bála o nemocného otce.

All winter she worried about her sick father.

The difference is real and you hear it daily: Bojím se psa = "I'm afraid of the dog" (the dog scares me); Bojím se o psa = "I'm worried about the dog" (something might happen to it).

💡

One little preposition flips the whole meaning. Bát se with a bare genitive = the thing is a danger to you. Add o + accusative and the danger runs the other way — you fear for the thing. Watch the case jump too: psa is genitive (afraid of), but o psa is accusative (worried about).

Second-position se: where the clitic sits

The reflexive se is a clitic — an unstressed little word that must occupy the second position in its clause, right after the first stressed unit. It cannot open a sentence and usually cannot be stranded at the end.

Já se bojím.

I'm afraid. (with emphasis on 'I')

Vždycky se bojím létání.

I'm always afraid of flying.

When there is also a past-tense auxiliary, the order inside the clitic cluster is fixed: auxiliary before se, giving jsem se, jsi se (often contracted to ses).

Bál jsem se, že tě vzbudím.

I was afraid I'd wake you. (male speaker)

Bála ses tam jít sama?

Were you afraid to go there alone? (to a woman; jsi se → ses)

The past tense

The past is built from the l-participle on the bá- stem (long á) plus the auxiliary and the ever-present se.

Subject	Participle + clitics	Meaning
masc. sg.	bál jsem se	I was afraid
fem. sg.	bála jsem se	I was afraid
neut. sg.	bálo se	it was afraid
masc. anim. pl.	báli jsme se	we were afraid
fem. pl.	bály jsme se	we were afraid

The future and the imperative

Bát se is imperfective, so the future is the analytic budu-future — and notice the se slips in right after the auxiliary: budu se bát, not budu bát se.

Person	Future
já	budu se bát
ty	budeš se bát
on / ona / ono	bude se bát
my	budeme se bát
vy	budete se bát
oni	budou se bát

The imperative is boj se (sg.), bojme se (let's), bojte se (pl./formal). In practice you will meet the negative imperative far more often — neboj se / nebojte se, "don't be afraid," one of the most common comforting phrases in the language.

Neboj se, všechno dobře dopadne.

Don't be afraid, everything will turn out fine.

Common mistakes

❌ Bojím psa.

Incorrect — bát se is reflexive; the se cannot be dropped.

✅ Bojím se psa.

I'm afraid of the dog.

❌ Bojím se pes.

Incorrect — the thing feared takes the genitive, not the nominative.

✅ Bojím se psa.

I'm afraid of the dog.

❌ Báju se tmy.

Incorrect — the present runs on boj-, not on the infinitive bá-.

✅ Bojím se tmy.

I'm afraid of the dark.

❌ Se bojím.

Incorrect — the clitic se can't start a clause; it must sit in second position.

✅ Bojím se.

I'm afraid.

❌ Bojím se o psa, je nebezpečný.

Wrong construction for 'afraid of' — o + accusative means 'worried for', not 'scared of'.

✅ Bojím se psa, je nebezpečný.

I'm afraid of the dog, it's dangerous.

Key takeaways

Infinitive bá- (bát se, budu se bát), present boj- (bojím se, bojíš se, bojí se…) — a fixed alternation.
The verb is always reflexive: never drop the se.
The thing feared goes in the genitive: bojím se psa, tmy, výšek — or a že-clause, or a plain infinitive.
bát se o + accusative is a different, narrower meaning: "to fear for, worry about" (bojím se o tebe).
The clitic se lives in second position; with the past auxiliary the order is jsem se (or contracted ses).

Now practice Czech

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Czech→