The blood of Vietnamese, Khmer, Cham, Rhade, Sedang and Stieng populations of the Republic of Vietnam was studied for hemoglobins, glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase and adenylate kinase by starch gel electrophoresis. Plasmodium falciparum malaria parasite rates were obtained in all groups but the Stieng. The prevalence of glucose-6-phosphate dehydrogenase deficiency was lowest in the Sedang (0.004), the Vietnamese (0.014) and the Rhade (0.023). The highest prevalence of glucose-6-phosphate dehydrogenase deficiency was found in the Stieng (0.153). The lowest frequencies of hemoglobinE were in the Vietnamese (0.025) and the Sedang (0.029). All other groups had high frequencies of hemoglobinE, the highest being the Stieng (0.365). The prevalence of phosphogluconate dehydrogenaseB ranged from 0,000 in the Stieng to 0.054 in the Vietnamese. The Vietnamese were not differentiated from the Sedang at the glucose-6-phosphate dehydTogenase or the hemoglobin loci but were differentiated at the phosphogluconate dehydrogenase locus. Using the three markers most of the populations studied in South Vietnam were distinguishable one from the other. There was variable correlation between the frequency of hemoglobinE and the prevalence of glucose-6-phosphate dehydrogenase deficiency. A correlation of the endemicity of falciparum malaria and the frequency of glucose-6-phosphate dehydrogenase deficiency and of hemoglobinE was inconclusive. The frequency of the adenylate hinaseZ allele was low to absent. Adenylate hinase3 was found in the Khmer and in the Stieng.