This study was performed to investigate the effect of dietary magenesium on stress reactions in rats having abdominal surgery. Sixty three male rats of sprague-dawley strain were blocked into 3 groups : rats fed regular magnesium (0.05% Mg: control) rats receiving regular magnesium with surgery(Mg-adeq : S) Five weeks after feeding abdominal surgery was performed and randomly chosen 7 rats from each group were sacrificed on 1, 3 and 5 days after surgery. Te following were found ; 1) Rats fed marginal magnesium showed significantly elevated urinary urea nitrogen urinary potassium and plasma glucose compared controls only one day after abdominal surgery but not 3 days or 5 days after surgery 2) Rats fed adequate magnesium did not show any significant change in metabolic stress indicator after surgery. 3) Plasma free fatty acid and cortisol level were not different among groups. 4) Decreased plasma magnesium and potassium level were found in rats fed marginal magne-sium and sacrificed one day and three days after surgery.