24 cases of non-immune feto-placental hydrops which were diagnosed by ultrasonography are presented. The precise etiology was possible in 21 of the cases using chromosome analyses, radiological assessments and carefully conducted post mortem examinations. The cause was maternal in 3 cases and due to fetal pathology in 18 cases, of which 5 were due to chromosome abnormalities. Three recessive autosomal syndrome, 9 malformations and in particular cardiac malformations and one twin pregnancy with transfusion from one fetus to the other were diagnosed. These features, which can be compared with those already in the literature, show that most of these cases of hydrops are due to genetic fetal defects and demonstrate how important it is to carry out chromosome analyses and systematic anatomo-pathological investigations. The results of these tests will indicate the way the doctors should look after the mother during pregnancy and how to deliver these mothers in subsequent pregnancies.