The clinical and hematological features of 202 Sicilian subjects with sickle cell disease are reported, 41 being homozygous for beta s (beta s beta s), 64 with beta zero thal beta s (beta zero beta s), and 97 beta+ thal beta s (beta+ beta s). Analysis of the findings showed that the disease observed in Sicilians is of intermediate severity and falls between the severe form observed in patients of African origin and the milder one seen in subjects of Arabian origin.