To investigate if the postglacial dispersion of mountain hares (Lepus timidus) into the present geographically separated ranges in Europe has produced marked gene pool differentiation, 209 individuals from Scandinavia, Russia, the Alps, Scotland, and Ireland were screened for allozymic variability at 40 structural gene loci by horizontal starch gel electrophoresis. Polymorphisms were detected at 13 loci. Most alleles were identical with those of brown hares (Lepus europaeus) studied earlier in Europe. Average expected heterozygosity (2.0-5.0 %) and rates of polymorphism (8.5-29.4 %) in regions or subspecies were comparable to those of local samples of European brown hares studied earlier. Despite a high amount (31.3 %) of "private alleles", genetic distances (NEI's 1978 D: 0.000-0.008 among subspecies, and 0.000-0.017 among regions) were similar to those found among local samples of central European brown hares. This indicates low genetic differentiation among gene pools of subspecies or regions. Also, relatively low mean F-ST values (0.157 for regions, 0.14 for subspecies) and low numbers of significantly differing allele frequencies indicated little genetic differentiation. WRIGHT'S (1978) hierarchical F-statistics revealed that less than 1 % of the relative genetic variation was partitioned among subspecies but 13.6 % among regions within subspecies. All results conform to the hypothesis of a quite panmictic gene pool of late-glacial and postglacial mountain hares in Europe. They also support the view that no severe drift has occurred in postglacial populations during the colonization of the present ranges.