A prospective study of the risk of postoperative local and general infectious complications was realized on 93 patients undergoing elective general surgery. The factors usually known to favour these septic complications, such as the length, the importance of the operation, as well as a preoperative loss of weight and thoracic or abdominal surgery are significantly demonstrated. Preoperative laboratory results bring no significant predictive information. On the contrary, when the immune defense mechanisms (determined by the cutaneous sensibility to ubiquitous antigens) were absent or very low before surgery, these patients significantly developed more septic postoperative complications.