Chestnut cultivation is economically of interest in Greece for timber and nut production. However, no information exists on the genetic variability of Hellenic populations. In each of two geographically distant areas, winter buds and seeds were sampled in one natural old-growth and one coppice population of chestnuts (in total four populations). Eight enzyme systems were studied. Genetic variability within and between populations was found to be high and can be regarded as the highest reported among natural European populations. The comparison between old-growth natural and coppice populations showed no statistically significant differences in heterozygosity. Seven quantitative parameters were also recorded. Analysis of variance indicated significant differences between the populations studied. The high diversity observed in genetic and quantitative variation is very important for both the development of breeding applications and the conservation of the species' genetic resources.