Fetal hydrops (hydrops fetalis) remains a significant cause of fetal and neonatal mortality. The decreased incidence of rhesus iso-immunisation due to prophylaxis with rhesus immune globulin (anti-D), improved antenatal ultrasound screening, and advances in neonatal intensive care have greatly altered the clinical outlook in this condition. A retrospective review of all 27 liveborn cases of hydrops in the Royal Maternity Hospital, Belfast in the period 1974-89 showed that in the last five years 40% of cases were non-immune in origin. The mortality rate fell from 100% in the first part of the study to 50% in the second.