Testicular juvenile granulosa cell tumor (TJGCT) occurs predominantly in infancy and may be associated with sex chromosomal abnormalities. We report a fetus aborted because of cytogenetically confirmed complete XXY triploidy. External genitalia of the fetus were female, with a short and patent vagina. The tumor presented as an abdominal multicystic mass with typical histologic and immunohistological features of JGCT. It was connected with a tubular uterus-like structure. The other gonad was an inguinally localized testis that showed histologically a Sertoli cell adenoma. Malformations typical for triploidy were also present: agenesis of the corpus callosum, stenosis of the pulmonary ostium, and hypoplasia of the lungs and adrenals. To our knowledge this is the first case of TJGCT in a triploid fetus.