Serum choline concentrations decrease during and after surgery. We undertook this study to determine whether the decrease of choline is associated with an increase in stress hormones. In 16 patients undergoing abdominal surgery with general anesthesia, circulating choline cortisol, prolactin, adrenocorticotropic hormone (ACTH) and beta-endorphin levels were measured before, during and after surgery. Choline levels decreased by 41% (P < 0.01) during surgery, remained 15-38% decreased for 48 h, and returned to preoperative values 72 h after surgery. The decrease in serum choline was associated and inversely correlated with the increase in serum cortisol (P < 0.001; r = -0.642), prolactin (P < 0.001; r = -0.756), beta-endorphin (P < 0.001; r = -0.726) and ACTH (P < 0.01; r = -0.458). In conclusion, we found that abdominal surgery induces a decline in serum choline associated with an increase in circulating cortisol, prolactin, ACTH and beta-endorphin. (C) 2002 Published by Elsevier Science Ireland Ltd.