The efficacy of the addition of prednisolone to tamoxifen as adjuvants to mastectomy in patients with primary breast cancer who were at a high risk of recurrence was investigated in a randomized trial. Primary carcinomas were collected from a series of 169 patients with loco-regional disease, undergoing mastectomy. The activities of alpha-glycerolphosphate dehydrogenase and 6-phosphogluconate dehydrogenase in the carcinomas were estimated biochemically and the ratio of the two enzymes was used to as the parameter to determine the risk of recurrence. 116 patients with a high risk of recurrence within five years of mastectomy were then randomized to either tamoxifen (2x20 mg/day) or tamoxifen+prednisolone (3x2.5 mg/per day) until recurrence. The patients are currently followed quarterly. The data were analysed at a median follow-up of 26 months (range 7-62 months). The probabilities of both disease-free and overall survival were not significantly different in either arm of the trial, indicating that there is no advantage in combining prednisolone with the antioestrogen. Recently, similar findings in terms of response have been reported for patients with metastatic disease treated with the same combination, raising doubts over the role of prednisolone in the management of patients with endocrine treatments.