Data are reported about the occurrence of glucose-6-phosphate dehydrogenase deficiency (G-6-PDD) and abnormal hemoglobins in a sample (316 males and 679 females) of the Negroid population of Porto Alegre, Brazil. The prevalence of double carriers (AS/G-6-PDD) was that expected from the isolated incidence of both anomalies. A review of the literature shows similar results for 3491 males and 289 females from African and American Negroid groups both from areas with and without malaria. Therefore there seem to exist no grounds for postulating an adaptive interaction between these two polymorphisms.