Craniopharyngiomas represent the second most frequent tumor of the intra- and suprasellar region in man. They account for 2–3% of all intracranial tumors (Svolos, 1969: 1.94%; Zülch, 1956: 2.7%; Russell and Rubinstein, 1971: 3%). Our own series contains 92 pituitary adenomas and 16 craniopharyngiomas (17%) whose ultrastructure has been examined. The youngest patient was 3; the oldest 55 years old. Eight patients were in the first decade of life, 4 in the second, and 4 in the third, fourth and fifth. The age distribution shows the same predominance of patients in the first two decades of life as seen in other series (Bailey et al., 1939; Cushing, 1932 b; Frazier and Alpers, 1931; Gordy et al., 1949; Love and Marshall, 1950; Northfield, 1957) although this shift is somewhat more pronounced in our material. There were 8 male and 8 female patients. The tumors were usually located in the suprasellar region. They frequently showed intrasellar, retrosellar, and parasellar extensions. One cystic craniopharyngioma showed an exclusively intrasellar location (no. 11/73). Two had grown into the third ventricle and were therefore removed on a transventricular approach.