Allozyme electrophoresis of 14 loci provided information on the distribution of the two central European subspecies of the fire salamander, Salamandra salamandra salamandra (dotted taxon) and S.s.terrestris (striped taxon), along an east-west-transect in Germany. 2183 larvae from 48 populations situated in 14 mountain ranges were studies. A broad (about 140 km wide) zone of intergradition between the two forms is described, ranging from the Hunsrück Mountains in the west to the Spessart in the east. Within this hybrid zone the populations are panmictic. Focussing on the Rhenish Slate Mountains, the western border of the hybrid zone is described in detail. A comparison between allozyme data and morphognostical data (drawn from literature) on the dorsal pattern indicates a discordance between the two data sets. Consequently, the dorsal pattern is ruled out as an indicator for the detection of hybrid populations.