OBJECTIVE To determine the accuracy of midtrimester diagnosis of fetal abnormality by examination and investigation of fetuses after induced abortion. METHODS Prospective study over five years of fetuses aborted in the midtrimester because of abnormalities detected by ultrasonography and amniocentesis. Techniques included a full external examination by a clinical geneticist with experience in dysmorphology and other investigations including necropsy. METHODS Regional genetic centre. METHODS Clinicians working within the North Western region who wished to use the service offered. RESULTS 133 Fetuses were aborted because of abnormalities detected on ultrasonography and 115 because of abnormal findings on amniotic fluid analysis. In a further two cases fetal abnormality was diagnosed by molecular genetic and biochemical techniques. Among the fetuses with abnormal scans the pretermination diagnosis was changed or refined in a way which affected genetic counselling in 53 of 133 cases. Among the 115 fetuses diagnosed as abnormal by amniocentesis the pretermination diagnosis was confirmed in 112 cases and altered in three. CONCLUSIONS Fetuses aborted because of abnormalities detected by screening should be examined by suitably experienced clinicians, both for accurate genetic counselling of the families and for quality control of the tests employed.