Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest red cell enzymopathy in humans and has an X-linked inheritance. It has been reported from India more than 30 years ago and the prevalence varies from 0-27% in different caste, ethnic and linguistic groups. The major clinical manifestations are drug induced hemolytic anemia, neonatal jaundice and chronic non-spherocytic hemolytic anemia. Individuals with G6PD deficiency have a selective advantage against falciparum malaria. Thirteen biochemically characterized variants have been reported from India. At the molecular level, G6PD Mediterranean is the most common deficient variant in the caste groups whereas, G6PD Orissa is more prevalent among the tribal of India. The third common variant seen in India is G6PD Kerala-Kalyan.