Congenital intracranial tumors are very rare and only account for 0.5-
1.5% of all childhood brain tumors. Even rarer are those with prenatal
manifestation. The most common of these present at birth are teratoma
s, which show divergent differentiation with 90% of them containing ti
ssues from all three germ layers. We report a rare case of an intraute
rine congenital immature teratoma in a female fetus at 23 weeks of ges
tation, which was sonographically diagnosed in vivo by detection of th
e tumor and associated craniomegaly. Because of the poor prognosis, te
rmination of the pregnancy was induced by Rivanol instillation. The ce
rebral tumor was confirmed at autopsy and was not associated with any
other malformations. Histological and immunohistochemical features of
this tumor are presented.