ABSTRACT Introduction: The Band 3 is a red blood cell protein that carries the Dia and Dib antigens from the Diego blood system. The SLC4A1 gene encodes Band 3; Band 3 Memphis is a polymorphism of normal Band 3 and has two variants, but only the variant II carries the Dia antigen. Objectives: Describe the frequencies of the DI*A and DI*B alleles and the Band 3 Memphis among blood donors, sickle cell disease (SCD) patients and Amazonian Indians. Methods: A total of 427 blood samples were collected and separated into three groups: 206 unrelated blood donors, 90 patients with SCD and 131 Amazonian Indians. We performed DI*A/B, normal Band 3 and Band 3 Memphis genotyping, using the Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR–RFLP). Results: The frequency of the DI*A/DI*A genotype was 0.5% in blood donors and it was not found in other groups. The frequency of the DI*A/DI*B was higher in Amazonian Indians (33.6%) and the frequency of the DI*B/DI*B was highest in blood donors (92.2%). All 105 individuals tested were positive for the presence of normal Band 3 and of these individuals, only 5/105 (4.8%) presented the Band 3 Memphis mutation. Conclusion: We observed a higher frequency of the DI*B allele in blood donors and a low frequency of the DI*A/DI*A genotype in all groups studied. The Band 3 Memphis was found in a higher frequency in the blood donor group. Our findings highlight the importance of analyzing different population groups to gain a better understanding of the genetic association of blood group antigens. Introduction system SLCA SLC SLC4A variants antigen Objectives DIA DI DIB B (SCD Methods 42 20 9 13 DIAB DI*A/B genotyping PCR–RFLP. PCRRFLP PCR–RFLP . PCR RFLP (PCR–RFLP) Results DIADIA 05 0 5 0.5 DIADIB 33.6% 336 33 6 (33.6% DIBDIB 92.2%. 922 92.2% 92 2 (92.2%) 10 5105 5/10 4.8% 48 4 8 (4.8% mutation Conclusion studied 1 (PCR–RFLP 0. 33.6 (33.6 92.2 (92.2% 510 5/1 4.8 (4.8 33. (33. 92. (92.2 51 5/ 4. (4. (33 (92. (4 (3 (92 ( (9