Isozyme frequencies in six wild-caught populations of Aedes albopictus (Skuse) from various parts of Thailand were compared using starch gel electrophoresis. Four populations were sampled from the south of the country, one from Samui Island and three from the mainland. The remaining two populations were obtained from central (Bangkok) and northern (Tak) Thailand. There were large differences in allele frequencies at two of 22 loci: Glutamate oxaloacetate transminase-2 (Got-2) and Hexokinase-1 (Hk-1). Got-2 (allele 100) was absent from the Bangkok population, whereas it was observed in high frequencies in all other populations. The Bangkok population showed the highest percentage of polymorphic loci (63.6%), whereas the population from Tak demonstrated the smallest percentage of polymorphic loci (18.2%).