Non-immunologic hydrops fetalis has been reported in association with such conditions as maternal diabetes mellitus, fetal infection, multiple fetal malformations (particularly cardiac), congenital nephrosis, homozygous alpha-thalassemia, prenatal closure of the foramen ovale, sublethal umbilical or chorionic vein thrombosis, and parabiotic syndrome.1-3 To our knowledge, the following case represents the first reported instance of fetal and placental hydrops associated with a tumor which acts as a fetal arteriovenous malformation. A female infant was delivered to a 38-yearold Japanese woman at a calculated gestational age of 32 weeks. One previous pregnancy with the same Caucasian father had resulted in a living, normal child.