DNA samples from seven G-6-PD deficient Mexican mestizo patients were analyzed. Three different G-6-PD genotypes were observed: G-6-PD A-202A/376G (three patients), G-6-PD A-376G/968C (three patients) and G-6-PD Seattle844C. The present results, along with previous reports, suggest not only G-6-PD A-genotypes are relatively common but also G-6-PD deficiency seems to be heterogeneous at DNA level in Mexico.