The postoperative wound infection experience in 11 Israeli hospitals wasinvestigated with two objectives: (1) to utilize the variability amonghospitals for a better understanding of the determinants of theseinfections, and (2) to present surgeons and infection control teams withinformation upon which they can take action. This article summarizes themethods that were applied to maximize the uniformity of information obtainedfrom hospitals. (1) The same kind of patients were sampled in everyhospital. (2) The data collection system was standardized, and analyzed forerrors. The overall error rate was small (2%) but there were potentialproblem areas, such as missing information on underlying diagnoses (12%).Few errors (1%) were found in the nurses' observations of the wounds. (3)All wound infections were diagnosed in a uniform manner by convening a panelof four specialists at the central Israeli Study of Surgical Infections(ISSI) office. (4) The definition of infection that was finally chosen forthis multicenter study had to be broadened to include, in addition to pus,“discharge other than pus,” because of the higher reliability among panelmembers. This definition was also clinically valid in terms of morbidity.(5) The rate of postdischarge infections was estimated and was not found tobe related to the discharge policies in the various hospitals.