A comparative electrophoretic karyotyping study was performed with several certified authentic strains of the four species that could be distinguished by nuclear DNA (nDNA)-nDNA reassociation data within the sensu stricto group of the genus Saccharomyces. A multivariate analysis of the polymorphisms observed in pulsed-field gel electrophoretic profiles (numbers and molecular weights of separated units) revealed that the strains could be separated into four clusters that corresponded to the taxa that were distinguished on the basis of nDNA comparisons. Discrepancies between nDNA reassociation data and membership in the corresponding clusters were observed only with two strains of Saccharomyces paradoxus. Blind tests carried out with additional industrial strains confirmed the general validity of the statistical model created for comparison of karyotypes within the species included in Saccharomyces sensu stricto.