To compare the features of sickle-cell anemia in Brazil with those in other locales, we studied the effects of the beta-globin-like gene cluster haplotype and alpha-thalassemia upon the clinical and hematological features in 85 patients, The distribution of haplotypes differed from that in the United States and Jamaica, The Central African Republic (CAR) haplotype predominated; 34% of patients were CAR haplotype homozygotes, 45% CAR/Benin homozygotes, and 71% Benin homozygotes. No Senegal haplotype chromosomes were observed, alpha-thalassemia was present in 17.5% of patients, HbF levels were higher in Benin homozygotes, compared with the other two groups (P < 0.05). Nearly half the patients with a CAR haplotype had leg ulcers, compared to 12.5% of the Benin homozygote group; stroke did not occur in alpha-thalassemia carriers, but neither result was statistically significant. As in other studies, our results indicate that the CAR haplotype may be associated with more severe disease. (C) 1996 Wiley-Liss, Inc.5327276