Population samples of drosophila melanogaster and Zaprionus indianus, collected along 20° latitudinal range of the Indian subcontinent, were analysed electrophoretically as well as with heat denaturation technique for patterns of allozymic variation at Adh and Est loci. The AdhF and Est-6S allelic frequencies in D. melanogaster; and AdhF and Est-1F allelic frequencies in Z. indianus were found to be positively and significantly correlated with increasing latitude. The consistency of the direction of geographical clinal variation across different drosophilids and among continental populations of D. melanogaster; and the occurrence of genic divergence at these loci provide evidence for balancing natural selection mechanisms to maintain such latitudinal allozymic variation in two different colonising species.