Much of the research dealing with the semantics of prepositions has focused on their intralexical, i.e.polysemous structures (e.g. Lakoff 1987, Taylor 1993, Šarić 2008). As a consequence, theirinterlexical semantic relations, such as antonymy, were neglected as a focus of research. On the other hand, most approaches to antonymy focus on the word classes of adjectives and nouns andthus do not investigate prepositional antonymy (see Lyons 1977, Cruse 1986, Jones et al 2012).Therefore the focus of the present research is to provide a systematic description of antonymyrelations of prepositions in Croatian and Danish, focusing on directional and locational opposites. Inorder to systematically compare antonymy relations between the two languages and explorepossible regularities, we discuss the same semantic content prototypically being encoded by the'preposition + case' in Croatian (iz:Gen 'out of') and 'adverb + preposition' construction in Danish (udaf 'out of', cf. English out of). With respect to identifying antonymy relations we apply the methodsof substitutability and co-occurrence of antonyms (Justeson and Katz 1991, Jones et al. 2012),developed primarily for adjective antonyms and evaluate their application to prepositional data.Extensive corpusanalysis in both languages aims to reveal the specific semantic properties andconstructional patterns of antonymy pairs, particularly the relation of antonymy to: a) the syntactic-semantic properties of constructions (e.g. Source-Goal opposites in motionconstructions) and b) theconceptual content profiled by antonymy pairs (Cro. u:Acc–iz:Gen; Da. ind i-ud af 'into–out of'–container / Cro. u:Loc–izvan:Gen 'in – outside', Da. hjemme hos-ude hos 'home-out'–centre-periphery). Antonymy is thus regarded as a conceptual and constructional phenomenon which canbe used to provide new insight into prepositional semantics and expand our knowledge of theorganization of lexical relations and their interaction within language use.