Inflammation is an essential component of the first phase of anastomotic wound healing, And it is suppressed by corticosteroids. The anti-inflammatory effect of corticosteroids is largely responsible. for. the impairment of wound healing in bowel anastomosis. It has been reported that local application of granulocyte-macrophage colony-stimulating factor (GM-CSF) improves the healing process in dermal wounds. In the present study, we investigated the effects. of locally injected GM-CSF on anastomotic wound healing in long-term corticosteroid treated rats. Eighty male Sprague-Dawley rats were randomized into four groups. 1: control, 2: steroid, 3: steroid + local GM-CSF, 4: steroid + systemic GM-CSF. In groups 2, 3, and 4, methylprednisolone (,5 mg/kg) was injected IM daily for 14 days. After 14 days, following anesthesia and laparotomy, colonic anastomosis was performed 3 cm. away from the peritoneal reflection. In group 3, 50 mug GM-CSF was injected into the perianastomotic area. In group 4, 50 mug GM-CSF was applied subcutaneously, On postoperative day 3, repeat laparotomies were performed and bursting pressures, hydroxyproline levels, and histopathology examinations were studied. The mean values of bursting pressures and hydroxyproline levels in group 3, treated with steroid + local GM-CSIF, were significantly higher than that of the group and group 4 values. In the histopathology examination, the mean score of group 3 was significantly higher than that of groups 2 and 4. Our study indicates that local application of GM-CSF significantly improves. the impaired anastomotic wound healing in rats treated with long-term corticosteroid.