During the period of January to July 1980, a marked increase in the number of Pseudomonas cepacia isolates was observed in a microbiologic surveillance program. Although P. cepacia was isolated from wound specimens and vaginal cultures, the majority of isolates were of urinary origin from catheterized patients. Retrospective chart analysis of the patients failed to verify a causal pathogenic role for P. cepacia. However, fulminant sepsis subsequently developed in two hospitalized immunocompromised patients, with both blood and urine cultures positive for P. cepacia. Investigation revealed the presence of this organism in chlorhexidine (0.2 percent) mouthwash as well as other chlorhexidine antiseptic solutions used for routine urologic and obstetric procedures. The source of the P. cepacia was identified as the rubber tubing in the pharmacy through which deionized water passed during the dilution of concentrated (5 percent) chlorhexidine gluconate. In vitro tests demonstrated that P. cepacia was resistant to 0.2 percent chlorhexidine.