Fifteen cases of malignant sacrococcygeal teratoma were treated at our hospital over the last 32 years. These included five cases of endodermal sinus (yolk sac) tumor that arose in otherwise benign or immature teratoma, and ten cases of pure endodermal sinus (yolk sac) tumor. Most were females, and only one was a neonate. The presence of symptoms almost always indicated local extension or distant metastases. According to Altman's classification, all but two of these malignant tumors were Types III and IV. The resectability was low, but with aggressive radiotherapy and chemotherapy, second look operations in five have been possible with increasing optimism for survival. Two of five patients with secondary resections are alive and tumor-free almost two years after therapy was discontinued. So far, only the newborn is a long-term (14 years) cure.