Fetal ovarian cysts are common during pregnancy and after delivery. Most of these cysts are simple cysts that involute during pregnancy or in the first months of life. However, complicated cyst with a heterogeneous structure and also possible and can result in various complications: rupture, hemorrhage, ascites, edema of the labia, compression of other viscera, and ovarian torsion. In this case report we describe rare diagnosis of a complicated fetal ovarian cyst with edema of the labia and moderate ascites. The neonate had ambiguous genitalia with clitoromegaly. The newborn underwent surgery with oophorectomy. During the operation a uterus with fallopian tubes was found. The pathological findings showed a juvenile granulosa cell tumor FIGO Ia. Karyotyping revealed a mosaic of 45, X/ 46, X mar (Y) in the peripheral blood as well as in the granulosa cell tumor. Because of a right side inguinal hernia, the child underwent a second surgery. Specimen taken from the abdominal gonad and the inguinal region showed testicular and dysplastic ovarian tissue. There were elevated levels of androgens in the childs peripheral blood due to the granulosa cell tumor. In summary, this case report describes a fetus with true hermaphroditism and a juvenile granulosa cell tumor diagnosed as a complicated ovarian cyst in the 32(nd)week of pregnancy.