The clinical value of therapeutic suggestions during general anaesthesia was assessed in a double-blind randomised placebo-controlled study. 39 unselected patients were allocated to suggestion (n =19) or control (n = 20) groups who were played either recorded therapeutic suggestions or a blank tape, respectively, during hysterectomy. The patients in the suggestion group spent significantly less time in hospital after surgery, suffered from a significantly shorter period of pyrexia, and were generally rated by nurses as having made a better than expected recovery. Patients in the suggestion group, unlike those in the control group, guessed accurately that they had been played an instruction tape. © 1988.