A prospective randomized trial was carried out on 207 patients undergoing laparotomy using three different vertical abdominal incisions--midline, 'medial' paramedian incision and 'lateral' paramedian incision. The lateral paramedian incision is slightly more time-consuming to perform than the other two incisions but there is a statistically greater incidence of incisional hernia in midline and medial paramedian wounds than with the lateral paramedian incision. It is suggested that when a vertical abdominal incision is being considered the lateral paramedian should be the incision of choice.