Ten strains of Paramecium bursaria and also P. caudatum, P. multimicronucleatum, P. tetraurelia strains (as outgroups) were characterized by using Random Amplified Polymorphic DNA (RAPD), Amplified Ribosomal DNA Restriction Analysis (ARDRA) and sequencing of the non-coding ribosomal internal transcribed spacer (ITS) regions. RAPD analysis revealed that all Paramecium bursaria strains possessed characteristic band patterns; there was a correlation between the degree of differentiation of DNA revealed by RAPD-fingerprinting and the geographic origin of a particular strain. ARDRA riboprinting (using a fragment of SSU-LSU rDNA, about 3085 bp) with restriction enzymes DraI, EcoRV, HhaI, HindIII, MspI, PstI distinguished groups of P. bursaria strains with characteristic band patterns originating from different sites. Comparison of the 550 bp ITS 1-5.8S-ITS2 fragment showed differentiation (0.9%) of the P. bursaria strains as three main groups of strains connected by site of origin in the constructed tree.