OBJECTIVES We assessed the long‐term efficacy and toxicity of conservative surgery and radiotherapy in the control of pituitary adenomas.

DESIGN Retrospective study of patients treated at the Royal Marsden Hospital.

PATIENTS Four hundred and eleven patients with pituitary adenomas treated with conventional external beam radiotherapy at the Royal Marsden Hospital between 1962 and 1986. Two hundred and fifty‐two patients had clinically non‐functioning pituitary adenomas, 131 had hormone secreting tumours and in 28 patients the secretory status was not known. Three hundred and thirty‐eight patients had surgical intervention of whom only 11 had complete tumour excision. All patients received conventional fractionated external beam radiotherapy to a dose of 45–50Gy in 25–30 fractions.

MEASUREMENTS Actuarial progression free survival and overall survival and assessment of toxicity, particularly in terms of vision, requirement for hormone replacement therapy and incidence of second tumours.

RESULTS The actuarial progression free survival was 94% at 10 years and 88% at 20 years for all patients and 97% at 10 years and 92% at 20 years for patients with clinically non‐functioning adenomas. Only secretory status was an independent prognostic factor for disease control. The 10 and 20‐year survivals for all patients were 77 and 58% respectively. When compared with the normal population the relative risk of death was 1 76 (P<0 001) and no prognostic factors for survival were identified. The morbidity of radiotherapy was low. Visual deterioration, assumed to be radiation induced, occurred in 1–5% of patients and the risk of second brain tumour was 1.9% at 20 years. Fifty per cent of patients received hormone replacement therapy by 19 years.

CONCLUSION Conventional external beam radiotherapy as described here combined with conservative surgery is safe and effective in the control of pitutary adenomas. These results should form a baseline for comparison with new treatment strategies.