The emergence of Providencia stuartii as a hospital pathogen in a burn unit was demonstrated by routine infection surveillance. The organism was initially recognized in a burn wound and subsequently in urine or sputum. Compared to controls, those patients harboring P. stuartii were similar in age and percentage of body surface burned and were more likely to have been in one of the two burn unit rooms, (p less than 0.02). Infection with P. stuartii was independent of duration in the Intensive Care Unit or Burn Unit, and of number of visits to hydrotherapy or operating rooms (OR). Once patients were colonized with P. stuartii they had greater morbidity than non-colonized patients as evidenced by longer stays in the unit and increased visits to the OR for debridement. P. stuartii was isolated from air samples (5/14) more commonly than from the hands of personnel. In vitro tests suggested that extensive use of parenteral gentamicin and replacement of the antibacterial topical cream sulfamylon by silver sulfadiazine favored the emergence of P. stuartii over Pseudomonas aeruginosa as the predominant colonizing organism.