A programme for the prevention of beta-homozygous thalassaemia has been operating in Cyprus from 1973. From 1976 there has been an increasing gap between the number of homozygotes born and the number expected, calculated as 1 in 135 of the total births. In 1978 23 homozygotes are known to have been born compared with 71 expected, and in 1979, 18 compared with 77 expected. All cases may not have yet to come to notice. the programme consists of public education, population screening, genetic counseling, and antenatal diagnosis.