Presacral teratomas are seen most frequently during infancy and childhood. Eighteen children with presacral teratomas were seen at the Mayo Clinic between 1907 and 1953, inclusive. Seventeen were girls. The clinical and pathologic findings are presented. A mass in the presacral area usually is the only symptom as well as the only abnormal physical finding. Such a mass was seen at birth in 14 of the 18 patients. Occasionally symptoms or signs, or both, of obstruction of the urinary tract and/or the gastrointestinal tract constitute the presenting complain. Roentgenograms aid in diagnosis; other laboratory findings contribute little. Pathologically, the size of the tumor may vary greatly. It may contain almost any type of tissue. There was no orderly arrangement of the tissue in any case in our series. In 4 of the 18 cases malignant changes were found microscopically. This is in close agreement with the recorded incidence of malignant changes in presacral teratomas. It is interesting that in one case 2 types of tissue were involved in malignant metamorphosis. Adenocarcinoma is the commonest type of malignancy found, and this is usually papillary. Metastasis frequently occurs via the blood stream to the lungs. The lymph nodes likewise may be the seat of metastatic lesions. Surgical removal should be undertaken regardless of the size of the tumor on the age of the patient.