The paper is focused on the comparison of the Czech and Slovak party systems. The paper discussesthe notion of political cleavages developed in these party systems after the break of communist regime in 1989. Theauthors point out that although the communist period created deadlock between traditional cleavages raised from thesecond half of the 19th century, yet it is possible to analyse some politically-based cleavages in these twoparty arrangements. Main attention is paid to the processes of creation of particular cleavages and to the parties'responses. The Czech and Slovak cases are compared in broader perspective of cleavages of transformation. Theconceptual model of cleavages of transformation which is readjusted for post-communist Europe is sketched for thispurpose. The paper is concluded by the analysis of the contemporary situation of political cleavages in the CzechRepublic and Slovakia. The authors try to compare both cleavage structures and show the possibilities of the futuredevelopment. They try to point out that there is a possibility for the Slovak party system to become more consolidatedand for its cleavage structure to become more similar to the Czech example than it is now.