Allozyme electrophoresis was used to evaluate genetic variability in painted reed frog (Hyperolius marmoratus) populations from the Northern Province and the Eastern Cape. Sixteen protein-encoding loci were resolved, of which seven displayed allelic polymorphism. Average heterozygosity (H) values in two permanent H. m. taeniatus populations from the Northern Province (7.9% and 6.3%) did not differ substantially from each other nor from the geographically distant Eastern Cape H. m. verrucosus (9.1%). An isolated Northern Province H. m. taeniatus population displayed more polymorphism than any other group with H=14.1%, which can probably be attributed to the periodic influx of reed frogs following dry periods. Genetic distances and gene diversity (FST) values conformed with expected values for conspecific populations. The results attained concur with the hypothesis of increased genetic heterogeneity among populations of small and relatively sedentary animals