Introduction. In the Udmurt language, compound sentences with subordinate clauses are very productive. The means of communication in such syntactic constructions are conjunctions, allied combinations and, in some cases, correlates. The same conjunctions help convey different semantics. The purpose of this paper is to identify conditional, conditional-temporal, conditionally causal semantic relations expressed with the help of conjunctions, allied combinations, and other linguistic means, as well as the structural features of such syntactic constructions on the material of the Udmurt language. Materials and Methods. The research was based on the examples borrowed from Udmurt fiction. The author employed a set of research methods, such as descriptive; partial and continuous sampling; contextual analysis; transformation. The use of these methods made it possible to consider the specifics of the units under consideration on specific linguistic material. Results and Discussion. The article deals with the widely represented compound sentences with conditional, conditional-temporal and conditionally causal clauses in the Udmurt language. It has been established that sentences of a repeating real condition and consequence often combine the properties of conditional and temporary sentences; constructions with a single condition or consequence in the form of the present tense combine conditional and causal sentences, in the form of the future tense combine both conditional-temporal and conditional; in the form of the past tense combine sentences that have only the meaning of time or reason, the meaning of the condition is erased. The type of specific semantic relationships at the level of the deep structure of the sentence can be determined by the conjunction, the marker of recurrence, as well as the form of the multiple aspect of the verb. Conclusion. In the Udmurt language, the conditional-temporal meaning, as a rule, is expressed in complex sentences of a repeating real condition with the help of conjunctions ke, kuke ‘if (when)’; conditionally causal meaning is expressed in sentences of a single real condition with the conjunctions bere, dyrja ‘if (as)’, in which the connection between two non-repeating phenomena is expressed. The semantics of a compound sentence may depend not only on the conjunction used, but also on the type-time form of the verb-predicate, the semes of singleness or repeatability, additional lexical markers of singleness and multiplicity. The exact definition of meaning and contamination is possible only at the level of the deep structure of the sentence.