Three patients in a university hospital developed nosocomial infusion-related Pseudomonas pickettii bacteremia. Investigation identified six additional patients who had received intravenous fluid contaminated by P pickettii but did not become ill. All nine patients had had surgery, and each of these patients but only nine of 19 operated-on control patients had received intravenous fentanyl citrate in the operating room; the mean dose given to the nine case patients was far greater than that given to control patients. Fentanyl in 20 (40%) of 50 predrawn 30-mL syringes was shown to be contaminated by P pickettii. Contamination was caused by theft of fentanyl from predrawn syringes and replacement by distilled water contaminated by P pickettii. Narcotic theft by health care personnel may cause patients to suffer pain needlessly and can also result in dire unanticipated consequences, such as nosocomial bacteremia. Whereas drug testing in the workplace is highly controversial, we believe that testing of health care personnel is indicated when drug abuse or theft is suspected.