Prepositions and Case Government

The single most important fact about Czech prepositions is one that English gives you no warning about: every preposition governs a case. That means the noun after a preposition does not appear in its dictionary form — it takes a specific set of endings determined by the preposition itself. In English, a noun looks the same no matter which preposition stands in front of it (to the house, from the house, in the house, with the house). In Czech, that same noun changes shape each time, and the preposition is what decides which shape. Learn the preposition and you have not learned half the construction — you have learned half, and the case is the other half.

The core principle: prepositions select a case

Take the word dům (house) and watch what different prepositions do to it:

Three prepositions, three different endings on one and the same noun: domu, domu, domem. The noun is not choosing these endings — the preposition is demanding them. This is what linguists call government (in Czech rekce): a preposition governs, or rules over, the case of its object the way a verb governs the case of its object.

Because the ending lives on the noun, you cannot stop at choosing the right preposition. You also have to know that preposition's case, and then you have to be able to form that case. The good news: a given preposition almost always takes the same case, every time, forever. Once you know bez takes the genitive, it takes the genitive in every sentence you will ever write.

A case-by-case map of common prepositions

Most everyday prepositions cluster around four cases: genitive, dative, locative, and instrumental. (The accusative also has its share, and many of the most frequent ones live in the two-case group below.) Here is the working map.

A few worked examples so you can see the ending change with the case:

Notice how unpredictable the endings look from the outside — cukru, řece, tebe, Praze, divadlem — and how predictable the system actually is from the inside: each preposition reliably triggers one case, and each case has its own endings depending on the noun's gender and type. The cases are covered in detail on their own pages; this page is about the link between preposition and case.

One special case you can only reach through a preposition

The locative (also called the 6th case, 6. pád) is unique: it is the one case in Czech that never appears without a preposition. You will only ever see a locative noun after v, na, o, po, při, and a couple of others. So if you spot a locative ending, there is always a preposition lurking nearby — and conversely, those five prepositions are a reliable signal that a locative is coming.

Some prepositions take two cases — and the case carries the meaning

A handful of high-frequency prepositions govern two different cases, and switching the case switches the meaning. The classic contrast is motion vs. location: with na, za, nad, pod, před, mezi, o, the accusative signals movement towards a goal, while the locative or instrumental signals a static position. (v is two-case as well, but its accusative is temporal or idiomatic, not spatial — motion into a place is do + genitive, do domu, not v + accusative.)

So the same preposition na can govern either the accusative or the locative, and you choose between them by asking whither? (movement → accusative) or where? (position → locative). This two-case behaviour gets its own treatment, but it is worth flagging here so you do not assume that "one preposition = one case" is an absolute law. It is the strong default, with a small, important set of exceptions.

Common Mistakes

The errors below are the predictable result of importing English habits, where the noun never changes after a preposition.

Key Takeaways

• A Czech preposition governs a case: the noun after it changes its ending accordingly.
• Memorise each preposition together with its case as a single unit ("s
  • instrumental").
• A given preposition almost always keeps the same case — the rule is highly stable.
• The locative is the one case that only exists after a preposition.
• A small set of two-case prepositions (na, za, nad, pod, před, mezi, o) use the case itself to distinguish motion (accusative) from location (locative/instrumental); v is two-case too, but motion into a place is do
  • genitive, not v
    • accusative.