We attempted prenatal diagnosis of hemoglobinopathies in 15 cases--11 for beta-thalassemia and four for sickle-cell disease. Fetoscopy was used in seven cases, and placental aspiration in eight. One premature labor, with fetal loss, followed placental aspiration. Globin synthesis was assessed by incubation of samples with 3H-leucine and chain separation on carboxymethylcellulose columns. Homozygous disease was predicted in two pregnancies, which were interrupted, and the diagnosis confirmed. In one case homozygosity was suspected. A repeat test was advised but not accepted. The fetus had thalassemia trait. One pregnancy was interrupted despite our prediction of thalassemia trait. Eight pregnancies went to term. Seven predictions that the infants would not have homozygous disease were confirmed. One prediction of sickle trait proved to be sickle-cell disease. Although prenatal diagnosis of hemoglobinopathies is feasible, the present frequency of fetal loss and diagnostic error indicates need for improvement.