Since January 1979, at our Genetic Counselling Unit in Debrecen all pregnancies at high risk for any reason have been screened sequentially by serum alpha-fetoprotein estimation (at the 16th week) and by ultrasound examination (18th week). This screening policy covered 1200-1500 consultations per year. From July 1983, the same prenatal screening policy has been extended to cover the whole pregnant population of two large counties in Eastern Hungary. In a six-year period over 300 fetal malformations were diagnosed. Details of the screening policy and the main groups of malformations diagnosed prenatally are demonstrated.