Prognostic factors and results of therapy were analyzed in a retrospective examination of 121 patients with pituitary adenomas treated with surgery and postoperative irradiation (RT) from January 1954 through December 1982 at the Radiation Oncology Center, Mallinckrodt Institute of Radiology. The 10-year overall and disease-free survival for all patients was 85.1 and 89.4%. The expected survival for an age-, gender-, and race-matched population was not significantly distinct at 85.3% (p = 0.72). Follow-up of 94 surviving patients ranged from 3.4 to 29.5 years (mean, 11.7). Statistical analysis was performed for multiple prognostic factors including age, race, gender, disease bulk, visual field symptoms, disease type, surgical approach, and irradiation dose and volume. The only prognostic variable identified by univariate analysis to significantly alter disease-free survival was irradiation dose. Patients receiving 5000-5400 cGy had a tumor control rate of 94.1% (64/68) compared to 85.0% (17/20) for 4000-4999 cGy, 75.0% (18/24) for 3000-3999 cGy, and 28.6% (2/7) for less than 3000 cGy (p = 0.000059). Factors evaluated but established to be insignificant were age, race, gender, disease bulk, visual field symptoms, disease type, surgical approach, and irradiated volume. The 10-year disease-free survival by classification was 93.3% for patients with amenorrhea/galactorrhea, 89.9% for non-functioning adenomas, and 76.4% for acromegaly (p = 0.21). Overall improvement in visual field defects subsequent to treatment occurred in 48.4% (44/91) of those with visual field defects before RT and was significantly correlated with RT dose. The median time to progression of disease was 10.2 years with the last failure occurring at 25 years following the fulfillment of RT. Severe complications related to RT were apparent in 1.7% (2/121). None were known to have endured brain radionecrosis. Serious surgical complications occurred in 9.9% (12/121).