In a prospective study of 1243 operations the rate of postoperative wound sepsis was 9.3%. Factors associated with high infection rate were high age, emergency operations, long duration of surgical procedure, potentially contaminated and contaminated operations, diabetes and treatment with steroids. The frequency of wound sepsis was also increased in patients with long preoperative hospital stay or 12.5% as compared to 4.5% in patients with a preoperative stay of one day. Among patients with long preoperative hospitalization, high age, long operative procedures, contaminated operations and treatment with steroids were significantly more common. 85% of the patients with long preoperative hospital stay and wound infection had three or more other factors associated with increased frequency of wound sepsis. No patient had long preoperative hospital stay as the only factor associated with high rate of wound infection. These data indicate that long preoperative hospitalization is not in itself a causative factor in wound infections, but might be related to other factors associated with increased likelihood of wound sepsis.