Prenatal diagnosis has been performed in more than 11,000 fetuses at risk for hematologic diseases. This paper summarizes the data from 30 centers from 1974 to 1985: 70% had fetal blood taken for hemo-globinopathies, of which 93% were for thalassemia and 7% for sickle disorders; 13% had DNA analyses for hemoglobinopathies, 54% for thalassemia and 46% for sickle disorders; 17% were investigated for other hematologic diseases using fetal blood, while 0.1 % of the cases were studied for other diseases by DNA techniques. Error rates for all types of studies were under 1 %, and fetal losses below 4%. Approximately 95% of families received safe, accurate information