In this study, the distribution of the most common variants of glucose-6-phosphate dehydrogenase, G6PD*A- (G202A and A376G alleles), G6PD*A (A376G allele) and G6PD*Med (C563T allele), and the major alleles of the blood system Duffy (FY*A, FY*B and FY*BES), RBC variants that confer protection against malaria, were investigated in Afro-descendant communities along the Trombetas, Erepecuru and Cuminá rivers, in the rural area of the municipality of Oriximiná, in the northeast of the state of Pará, in the Brazilian Amazon. The gene discussed is G6PD; the disease is malaria.