The occurrence of enlarged spleens and its age distribution has long been used as a crude measure to estimate malaria endemicity in cross-sectional surveys. Spleen size, however, is influenced by several variables that should be considered if they are observed in a population under study. We hypothesized that spleen indices are dependent on distinct red blood cell polymorphisms. Accordingly, we expected a lower prevalence of splenomegaly among patients with the sickle-cell trait (HbAS), HbAC trait and G6PD deficiency than in patients without red cell disorders, possibly due to the lower incidence of malaria attacks in these individuals. In our survey, however, spleen rates and sizes did not differ significantly between HbAA-, HbAS- and HbAC-positive individuals. Furthermore, enlargement of spleens was found at similar frequencies in persons with and without glucose-6-phosphate-dehydrogenase (G6PD)-deficiency (G6PD-A(-)).