The article discusses English and Slovene phraseological units with onomastic components. The research is based on two databases: an English one comprising 172 phraseological units and a Slovene one consisting of 324 phraseological units. The phraseological units are studied to determine which proper names form components of English and Slovene phraseological units and how frequently they appear in English and Slovene. Then, the universality or cultural specificity of phraseological units in both languages is investigated, bearing in mind that phraseological units with onomastic components are very often culture-specific because they refer to a unique denotatum belonging to the national culture. As is evident from the analysis of English and Slovene phraseological units, reference in English as well as in Slovene phraseological units is often made to people or places with which the members of the respective culture are familiar. On the other hand, many phraseological units with the same origin are more universally used in several languages with the same cultural and historical background, which also holds true of English and Slovene. The final finding is that proper names that are components of phraseological units and which are characteristic of a given culture should be observed from different points of view, such as historical, geographical, cultural, linguistic, cross-linguistic and social, and that more thorough studies of phraseological units with an onomastic component would contribute to a higher level of cross-cultural awareness.