Over a two-year period, cysts of the fetal choroid plexus were diagnosed prospectively by routine second-trimester ultrasonography in five patients, representing 0.18% of the population scanned for standard obstetric indications. Gestational age at the time of diagnosis ranged from 16-22 weeks. The cysts were located in the posterior portion of the choroid plexus within the lateral ventricle. The maximum diameter ranged from 3-14 mm. In two cases, the cyst was noted to be bilocular. No additional anomalies were detected in any fetus. Follow-up sonography two to five weeks after the initial scan documented disappearance of the cysts in all cases. The course of pregnancy in these patients was otherwise uneventful, and all infants were normal physically and neurologically both at the time of birth and between four and 24 months of follow-up.