Malaysian, African and Thai Plasmodium falciparum isolates were cultured in vitro by the Trager and Jensen method (1976; 1977) and were later cloned by the limiting dilution method (Rosario, 1981). Forty-eight clones were obtained and were characterized by electrophoretic variations of GDH (NADP-dependent glutamate dehydrogenase)(EC. 1.4.1.4). It was found that they were pure clones because they possessed either GDH-1 or GDH-2 unlike their parent isolates which exhibited both GDH-1 and GDH-2.