As an approach to investigating the origin of sickle cell hemoglobin (hemoglobin S) in white persons of Sicilian ancestry, two groups of native Sicilians were tested for blood group evidence of African admixture. Among 100 unrelated Sicilians, the phenotypes cDe(Rho) and Fy(a-b-), and the antigens V(hrv) and Jsa, which are considered to be African genetic markers, were detected in 12 individuals. Among 64 individuals from 21 families with at least one known hemoglobin S carrier, African blood group markers were detected in 7 (11%). These findings indicate that hemoglobin S is only one of multiple African genes present in contemporary Sicilian populations. The occurrence of hemoglobin S in white persons of Sicilian ancestry is considered to be a manifestation of the continuing dissemination of the original African mutation.