In a prospective study involving 276 patients, stab wounds to the abdomen and lower chest with certain penetration into the peritoneal cavity were managed selectively. On the basis of physical findings, patients underwent either immediate laparotomy or close observation with frequent reexaminations and operation only if signs changed. The reliability of physical examination and the safety of nonoperative treatment in the absence of peritoneal signs were assessed. The overall incidence of major damage, including damage to the diaphragm, was 59.1 percent. Significant intraperitoneal visceral injury was found in 45.7 percent of patients with transabdominal stab wounds and in 25 percent of those with transthoracic stab wounds. Physical examination correctly predicted the findings in 90 to 96 percent of patients at initial assessment, with a sensitivity of 88.4 percent and a specificity of 93.9 percent. As delayed laparotomy after a change in signs during observation did not increase morbidity or hospital stay, and the unnecessary laparotomy rate in this study was 5.9 percent, we recommend a policy of selective management of abdominal and thoracic stab wounds with omental evisceration or other evidence of peritoneal penetration. Local wound care with amputation of the protruded omentum followed by close observation and monitoring of vital signs is safe surgical practice when no peritoneal signs or other indication for urgent exploration are present on admission.