Prepositions are included in the auxiliary types of words. For them in grammars, the authors emphasize that they have a relational role, that their meanings are generalized, and that they establish relations between words, although some grammaticians also acknowledge lexical meaning to them. Prepositions only come with dependent cases, most commonly with genitive, least commonly with dative, and with locative case prepositions are obligate. Prepositions can be described from various sides, as they are also found in the chapters of morphology, syntax and semantics, and beside that, the complexity of the description is also contributed by the fact that some suggestions can stand with more than one case, giving them different meanings or in some cases, the same meaning. Some prepositions appear regularly and frequently, others are already considered marked or outdated. For some, we are say that they have disappeared from use in the modern language, while some have left a mark in some phraseology or dialectisms. New expressions, combinations, constructions and a whole set of words that, over time and through the changing of language and with more open approach to the classification of word types also got the status of the propositions. The aim of this doctoral thesis, as the title itself states, is a comparative, contrastive description of the use of a genitive prepositions which, as an case of possessiveness, partitiveness and ablativity, binds to itself numerous suggestions that further enrich the list of meanings. Contrastive description was made on the corpus of the primary propositions in two Slavic languages - Ukrainian and Croatian. In the introductory part of the paper, motivation is presented in selecting the topic, means and method of analysis. Through a brief overview of the subject area, papers and authors were presented in the two analyzed languages in the subject of the prepositions, in the narrower or broader sense. The resources and selection of the literature that were used for the research in this paper work are shown in this introductory part. Grammatics were served for both languages. monolingual (explanatory) dictionary for both standard languages, etymological dictionaries and internet language corpora. The first part of the paper shows how are the prepositions, as one of the unchangeable types of words, described in Ukrainian grammars on the one hand, and in the Croatian on the other hand. Concepts and theories about the meaning and role of the prepositions are presented. It is stated which authors acknowledge to them only a relational role and which also recognizes them as a words with lexical meaning. Also, a description of the genitive case will be presented as a case that has besides himself the prepositions I am analysing in this paperwork. The genitive case will also be presented from the view of the Ukrainian and Croatian grammarians. In the central part of the paper, an analysis of all selected primary prepositions was made. This section describes the meaning of prepositions and examples. Prepositions are selected based on the principle of origin. For the Croatian language in the list of analysed prepositions are chosen those primary prepositions which are as such defined in the grammars E. Barić et al., and in the grammar of S. Babić et al., since only those two grammars, among those taken as relevant, the prepositions are classified and listed by the principle of origin. In the other two grammars used to describe the proposal, prepositions that are connected to the genitive case are not defined and listed by theirs origin. Thus, the list of Croatian language primary prepositions was made according to grammar E. Baric et al., And S. Babic et al. For Ukrainian language, this choice was made according to a very comprehensive and detailed dictionary of Ukrainian proposals in which primary and secondary prepositions were processed and in each of these prepositions it is precisely determined in which group it belongs to by the principle of the origin. The grammars does not specifies the exact list of proposals with each case distinct by the origin, i.e. by the characteristic primary - secondary. Because of this reason, the list of Croatian primary prepositions that are connected with genitive is longer than the one in the Ukrainian language. Some prepositions were included in that list are actually of the secondary origin, but they have lost an obvious connection with the word from which they originated, and they are ranked among the primary (underived) in these two Croatian grammars. On the Croatian side, the primary prepositions that are taken into consideration are: bez, do, iz, iza, izim, kod, mimo, nakon, od, osim, oko, preko, poput, pored, protiv, radi, s, spram, sred, suprot, u, unutar, uslijed, van, za, zbog. Ukrainian primary prepositions that were taken into consideration: без, в/у, від, для, до, з, за, з-за (із-за), крім, між, проти, ради, серед. In the analysis, first are presented, in alphabetical order, the prepositional pairs (pairs in the similarity of the sounding and meaning) (bez – без, do – до, iz – s – з, з-за (із-за), od – від, osim – izim – крім, protiv – проти, radi – ради, sred – серед, u – в/у, za - за), i.e. Croatian prepositions that have their equivalents in the Ukrainian. In such a pair, the Croatian proposal was first presented, followed by his Ukrainian analogue and, at the end, analysis of the compatibility and incompatibility regarding usage. In two cases it is not only about pair, but about trio (iz - s – з, osim – izim - крім). After that, it is presented, in alphabetical order too, the primary genitive prepositions that have no equivalent in the primary prepositions with the genitive case in the other analyzed language, first such Croatian prepositions(iza, kod, mimo, nakon, oko, preko, spram,suprot, poput, pored, unutar, uslijed, van, zbog), then Ukrainian (для, між). In such "non-pairs" the answer is given how such prepositions in the other analyzed language are translated, i.e. what can be found in their place. After the central part and the analysis follows the conclusion that shows the results of the analyzed prepositions and compatibility and incompatibility of these two analyzed languages have been demonstrated and the most important cognitions are distinguished in comparison. At the very end there is a list of literature, in alphabetical order, that served in the theoretical elaboration of the prepositions as one of the world classes, genitive case that binds all the elaborated prepositions in this paper and in a concrete analysis of the meaning of each individual preposition. Also, dictionaries and corpora from which are taken examples of usage the analyzed prepositions are also listed. The aim of this paper is to contribute to the description of the proposals in the Slavic languages, by comparing the prepositions in the Croatian and Ukrainian languages.