In January through August 1983, eight children developed wound infections after they underwent genitourinary reconstructive surgery at one hospital. Cultures of purulent drainage yielded Pseudomonas aeruginosa in two cases, Streptococcus faecalis in one case, both S. faecalis and Staphylococcus epidermidis in one case, and S. faecalis and other Gram-negative rods in four cases. A study in which uninfected children who had had genitourinary reconstructive surgery were used as controls revealed that all cases and controls had received cephalosporin prophylaxis. Antibiograms revealed that all organisms were resistant to the cephalosporin antibiotics tested. Risk of infection was associated with shaving (p less than 0.001, Fisher's exact test) and exposure to one nurse (nurse X) (p = 0.003, Fisher's exact test) and one surgeon (surgeon X) (p = 0.007, Fisher's exact test). Nurse X was the private scrub nurse for surgeon X; she was present only at operations surgeon X performed (p less than 0.001, Fisher's exact test) and had no reported or observed practices different from those of other surgical nurses. However, surgeon X had two practices that were notably different from those of other surgeons: 1) he used quaternary ammonium compounds, acetone/alcohol, and 1 per cent hexachlorophene for preoperative skin preparation; and 2) he prepared the operative site himself. In addition, he was observed to prepare the operative site by beginning centrally, moving peripherally, and returning to the central area with the same sponge. These findings suggested that the shaving of the operative site and the use of certain agents and/or different preparatory techniques may have contributed to increased risk of wound infections. These wound infections were caused by organisms resistant to the prophylactic antibiotic(s) used.