Objective    To evaluate whether laparoscopic colorectal surgery can reduce the risk factors that contribute to postoperative morbidity.     Methods    A total of 344 consecutive patients with colorectal diseases were randomized to laparoscopic surgery (n=170) or open operation (n=174). On admission

the demographics

comorbidity

and nutritional status were recorded. Operation variables

patient outcome

and length of stay were also recorded. Postoperative complications were registered by four members of staff not involved in the study.     Results    The overall morbidity rate was 26.5%

and the rate in the laparoscopic group (18.8%) was significantly lower than that in the open group (33.9%; P0.01). The patients in the laparoscopic group had a faster recovery of bowel function (P0.01) and a shorter length of stay (P0.01). In the whole cohort of patients

multivariate analysis identified open operation

duration of operation

and blood transfusion as risk factors for postoperative morbidity. In the open group

blood loss

blood transfusion

duration of operation

weight loss

and age were related to postoperative morbidity. In the laparoscopic group the only risk factor identified was duration of operation.     Conclusion    Most risk factors for postoperative morbidity in open operation group are not risk factors any more in the laparoscopic group

especially postoperative morbidity and length of stay are significantly reduced.