['Glucose-6-phosphate dehydrogenase deficiency (G6PDd) has been shown to protect against malaria infection and severe manifestations in African and Asia, but there is a scarcity of studies in the Americas. This study aimed to study the prevalence of G6PDd and its association with malaria occurrence in the Brazilian Amazon.', 'A cross-sectional study was conducted in the male population to estimate the prevalence of G6PDd and malaria infection. G6PD deficient samples were genotyped to identify the deficient variant. Number of previous malaria episodes and need for blood transfusion during malaria episodes were recorded by applying a standardized questionary.', 'From a sample of 1478 male individuals, 66 were detected as G6PD deficient, resulting in a prevalence of of 4.5% (95% CI = 3.44-5.56%). Fifty six G6PD deficient individuals (3.8%; 95% CI = 2.82-4.77) presented the G6PD A-variant mutation, while 10 individuals (0.7%; 95% CI = 0.42-0.97) severely deficient were genotyped as carriers of the G6PD Mediterranean variant. After adjusting for age, G6PD deficient individuals were less likely to report the occurrence of malaria episodes, and the protective effect was related to the enzyme activity, with carriers of the GG6PD A-variant presenting a 88% reduction (AOR: 0.119; 95% CI = 0.057-0.252; p < 0.001) and carriers of the Meditarrenean variant presenting 99% lower risk (AOR: 0.010; 95% CI = 0.002-0.252; p < 0.001) when compared to non-deficient individuals. On the other hand, G6PD deficient subjects reported higher need of transfusion during malaria episodes (p < 0.001).'] Are glucose-6-phosphate dehydrogenase deficient variants associated with reduced susceptibility to malaria in the Brazilian Amazon?