Of 149 horses that underwent 151 exploratory laparotomies for gastrointestinal disorders from September 1987 to May 1991, 107 (72%) were discharged from the hospital: 100 (66%) survived for >7 months, 94 of which returned to their intended use. Survival rate (64/80) for horses with caecum/large colon obstruction was significantly (P=0.003) higher than for horses with small intestinal obstruction (33/64). Prolonged surgery was associated with significantly (P<0.001) lower survival rates than short surgical time. In the large intestine, survival rate (15/29) for strangulated obstructions was significantly (P<.0.001) lower than for simple obstructions (52/58). Generalised septic peritonitis (9 horses) and bowel obstruction associated with adhesions (8 horses) were the most frequent fatal post-operative complications. The rate (6/44) of post-operative adhesions after small intestinal obstruction was significantly (P=0.006) higher than that (2/68) following large intestinal obstruction. The rate (8/55) of post-operative adhesion formation in horses that required enterotomy/enterectomy was significantly (P=0.003) higher than that (0/57) in horses that did not require gut wall incisions. Incisional suppuration developed in 42 horses and occurred with a significantly (P=0.028) higher rate (32/72) after caecum/large colon lesions than after obstruction at other sites, (10/42) but was not associated with known contamination at the time of surgery (P=0.806).