1. Plasma cortisols were measured in nine patients undergoing pelvic surgery under epidural anaesthesia.
2. Compared with response under general anaesthesia, the cortisol response was usually delayed and diminished, sometimes to an extreme degree.
3. No clinical problems were found to be associated with the very low cortisol levels, and the hypotension associated with epidural anaesthesia was neither related to the cortisol concentration nor corrected by glucocorticoid supplements.