Corticosteroid-induced acute psychoses in three Chinese patients receiving prednisolone 15-75 mg/d are described. The cases are compared with other cases of corticosteroid mental disturbances in the literature. It is concluded that the mental disturbance usually occurs within the first ten days of treatment, and presents most often in women, as either an acute manic or depressive episode accompanied by delusion and/or hallucinations. An exponential increase in the risk of the mental disturbance occurs as the corticosteroid dose increases.