During the years 1941 through 1973, 48 patients, 16 males and 32 females, with sacrococcygeal teratoma were seen at the Childrens Hospital of Los Angeles. Forty-four patients have been followed, three are lost to follow-up, and one patient died 2 wk after excision of teratoma. Of the 44 patients with follow-up, 26 had teratoma with mature tissues only, all these patients are living. Six patients had tumor containing mature and embryonic tissues. Of these, five are living and one died with metastases of malignant teratoma 1 yr after excision of the primary tumor. Of the remaining 12 patients, 11 have died during the first 4 yr of life due to malignant teratoma and only one is living without recurrence 15 yr after excision of teratoma containing frankly neoplastic tissues. Recurrence and/or metastasis of malignant sacrococcygeal teratoma was lethal in all instances.