Three cases of rare primary intracranial yolk sac tumor are reported. Two cases had a pineal location, whereas the third presented as a suprasellar mass. After the placement of ventriculoperitoneal shunts for relief of hydrocephalus, all of the patients developed metastases restricted to the peritoneum, as demonstrated by autopsy in one patient (Case 1) and clinical and radiographic evidence in two patients (Cases 2 and 3). The peritoneal metastases were directly associated with the death of one patient, but were successfully treated with chemotherapy in another patient, who is still alive more than 2.5 years after initial presentation. The value of ascitic fluid cytology and alpha-fetoprotein determination in the diagnosis of this complication was demonstrated in one patient. These cases emphasize the need for awareness of this mode of metastasis and its potentially lethal effect.