Susceptibility to infection in patients with obstructive jaundice is much more higher than non-jaundiced patients. The reasons for this are not completely understood. It is postulated that this may have some relation to changes of patients' immune function. This article reported the changes of splenocyte IL-2 production and T Suppressor cell activity in rats with obstructive jaundice. Meanwhile, we also investigated effects of cimetidine on immune function in rats with bile duct ligation. The results show that IL-2 production in obstructive jaundiced rats significantly decreased and T suppressor cell activity markably increased. Cimetidine could remarkably enhance IL-2 production and suppress T Suppressor cell activity. Abnormality of immune function may be one reason for high susceptibility to infection in patients with obstructive jaundice in perioperative period. Cimetidine, which could clearly improve immune function in rats with obstructive jaundice, might be a valuable agent for strengthening the capacity of fighting infection in patients with obstructive jaundice.