Mitochondrial malic enzyme (MEM) was examined by starch-gel electrophoresis in 182 brain samples from 102 male and 62 female subjects of Indian origin in Calcutta. Eastern India. The estimated gene frequencies of MEM were 0.56 for MEM1 and 0.44 for MEM-in this population. There was no difference in gene frequency between the sexes. No deviation from the Hardy-Weinberg equilibrium was observed. MES did not show any polymorphism. © 1980 S. Karger AG, Basel.