This paper reports the present results of an ongoing program aimed at preventing homozygous beta-thalassemia by means of heterozygote screening and antenatal diagnosis in the Sardinian population. Screening based on the knowledge of carrier frequency and types of thalassemia prevalent in this population was designed to discover all heterozygotes except the few silent beta-thalassemia carriers. Most of the couples at risk were informed and accepted testing. Information was conveyed by mass media, midwives and marriage registry offices. Antenatal diagnosis was accepted by the majority of the couples counselled. The results of antenatal testing were very accurate. There was only one misdiagnosis out of 949 pregnancies tested. This risk of fetal loss was 7.5%. The program was highly effective, as shown by the decline of the incidence of the homozygous state from 1:205 live births in 1976 to 1:557 in 1981.