Allozymic variability of 157 brown hares Lepus europaeus (Pallas, 1778) from eight sampling localities in Bulgaria was studied by horizontal starch gel electrophoresis of 50 putative structural gene loci. The present data were compared to an adjusted data set of brown hares from central Europe (Austria), published earlier, in order to test the hypothesis of increased genetic diversity in brown hares From the southeastern European zoogeographical crossroads region, a possible refuge for brown hares during the last glaciation period. No new polymorphic locus was detected, and only one new allele occurred at a low frequency in the Bulgarian hares. Nevertheless, two estimators of genetic diversity (average expected heterozygosity, Shannon-Weaver information index) where slightly higher in Bulgarian hares than in central European hares. In contrast, some alleles found earlier in various parts of central Europe did not occur in the Bulgarian samples. The latter finding suggests that gene pools of central European brown hares might have received gene flow from other parts of Europe during their postglacial (re-)colonization process. This accords to an alternative hypothesis of postglacial colonization of central Europe from both southeastern and southwestern refuges.