One hundred and sixty-two cases of suspected congenital abnormalities of the urinary tract notified to the Northern Region Fetal Abnormality Survey Register between the beginning of 1984 and the end of 1986 were studied. These cases represented 14.3% of total notifications, which in turn were 0.93% of total births. There were a further 25 cases notified but not due for delivery until early 1987; 10 of these were urological. Thirty-five cases (22%) notified proved postnatally to have normal urinary tracts and 21 (13.2%) had unsuspected urinary tract abnormalities. Of the 106 cases in which a suspected urinary tract abnormality was confirmed postnatally, confirmation was obtained at perinatal death in 32 and by ultrasound, radiographic and radioisotope investigation in the remainder; 34.5% of all urological cases registered and 75% of the confirmed survivors were treated surgically. The urological abnormality most frequently missed was posterior urethral valves. Attempts to diagnose the fetal sex were seldom made but when they were the prediction was usually male and usually correct. The perinatal mortality in this group was 0.43/1000 births, a contribution of nearly 4% to overall perinatal mortality in the Northern Region.