Postoperative wound infections following 5,260 selected procedures at a University Hospital were studied. These data were collected during a three year period using a single surveillance system. These data were compared with those of earlier reports. Accurate postoperative wound infection rates can be obtained as part of a total hospital surveillance program. Operative procedures should be subdivided, so that postoperative wound infection rates among different institutions can be reasonably compared. The major importance of prospective surveillance lies in the actual control of infections.