The clinical manifestations, pathological features and follow-up data on 12 cases of pituitary adenoma in patient less than 20 years old were evaluated. This group represented 8.5% of our 142 cases of pituitary adenoma from all age groups during the period of study. There were five males and seven females whose ages ranged from 13 to 19 years at diagnosis. Immunocytochemical staining demonstrated the presence of prolactin in 10 tumors, ACTH in one tumor and the remaining neoplasm was negative for the five major pituitary hormones (prolactin, hGH, ACTH, TSH, gonadotrophin). The results of the immunocytochemistry correlated appropriately with the clinical manifestations. Extension beyond the sella turcica at presentation was a common feature as evidenced by the high incidence of visual defects (75%). A complete excision was accomplished in only two patients. The aggressive behavior of these tumors was demonstrated by a recurrence rate of 50% and only a single long-term cure. Early detection and therapy, if possible, are essential for the successful management of pituitary adenomas in younger patients as implied by our study and other reports in the literature.