Phraseology, as a relatively young linguistic discipline, studies and describes idioms of a language whose meaning does not coincide to the amount of the connotation of their constituents. With the comparative analysis of the Croatian and English language the preservation of cultural elements in the language can be seen. Since phraseology is specific to each language, there are certain differences that can be found in English and Croatian idioms. The goal of this thesis is to analyze English and Croatian idioms and to compare and determine differences and comparisons. Two categories and two subcategories were established by comparative analysis. The first category consists of completely matching idioms, while the second category consists of partially matched idioms. The second category is divided into two further subcategories. The first subcategory contains idioms with identical structure and meaning, but discrepancies are found in their constituents. The second contains idioms with the same meaning but different structure.