In 10 Nigerian patients undergoing upper abdominal surgery the plasma cortisol concentration was slightly decreased after premedication with pethidine and atropine, and during anaesthesia without surgery. There was a small increase during surgery. None of these changes was statistically significant. There was a significant increase in the postoperative period however. Premedication caused a slight increase in blood sugar which remained steady during anaesthesia. There was a significant increase after 30 and 60 rnin of surgery, with a peak value at 60 min after operation. There were no significant changes in the mean values of plasma insulin concentration throughout the period of study. In a recent review of the world literature on anaesthesia and carbohydrate metabolism, Clarke (1973) concluded that Europeans and Japanese show a significant hyperglycaemic response to trauma under all types of anaesthesia, though it is less marked than the response of Jamaicans or Indians. This conclusion was based on the studies by Keating (1958) on Jamaicans, Cullingford (1966) on Indians, Clarke (1968 and 1970) on Europeans, and Oyama and Takazawa (1971a). Earlier reports by Barnicot and Wolffson (1952); Monnet, Baylet, and Reynaud (1952); Stirling and Keating (1958); and Phillips and Cohen (1959) indicated that the adrenal glands in Africans are less active than those of Europeans. However, recent studies of basal plasma cortisol concentrations in East and West