BACKGROUND AND OBJECTIVE: The present study was designed to determine the distribution and severity of sickle cell disease (SCD) in Italy. DESIGN AND METHODS: A questionnaire, requesting information about the cases of sickle cell disease that had been seen during previous years, was sent to all Italian centers of Pediatrics and Hematology. The questionnaire was simple and required personal, hematologic and clinical information. RESULTS: A total of 696 cases were reported. The distribution of registered patients shows that, although the S gene originated mostly in Sicily and Southern Italy, 20% of patients with SCD now live in Central and Northern Italy. The types of SCD reported were as follows: compound heterozygotes HbS-beta thalassemia, (S-Th, 518 cases); homozygotes for HbS, (S-S, 149 cases); compound heterozygotes HbS and another abnormal hemoglobin (21 cases). The population of patients with SCD is younger than the general Italian population. More than 90% of patients have had no crises or only a limited number, namely, up to 6/year. Infections ranged between 0 and 6/year. Splenomegaly was reported in 28% and 80% of adult patients with S-S and S-Th, respectively. The prevalence of gallstones was 48%. INTERPRETATION AND CONCLUSIONS: The survey established that 1) sickle cell disease is widely distributed in Italy; 2) while the clinical spectrum is extremely variable, severe forms are infrequent.