In spite of care taken by operating teams, a relatively large number of foreign objects are retained in patients' bodies after intra-abdominal surgery. One estimate is one per 1,000 to 1,500 laparotomies (opening of the abdomen). Four case histories are provided of patients who retained surgical sponges. In two cases, the two sponge counts had been performed by two different operating room crews because of a shift change. A third case had no record of sponge counts, and the fourth surgery occurred in another country. The frequency of retained sponges is probably grossly underestimated, since people do not like to discuss their failures. Septic (related to infection) complications are most likely soon after surgery, but sponges can be retained aseptically for years. Sponges with radiopaque markings can be seen on X-ray, but not all countries use such sponges. Trauma cases, where the crew is hurrying, are prime candidates for this kind of error. It is important not to misdiagnose retained sponges and initiate aggressive surgical procedures. Prevention is the best solution, and guidelines are provided. (Consumer Summary produced by Reliance Medical Information, Inc.)