Stenotrophomonas maltophilia is a motile, non-fermentative, gram-negative rod. It is one of the important nosocomial pathogens associated with substantial morbidity and mortality such as pneumonia and bacteremia in immunocompromised patients. It should be carefully examined in the course of identification because it is frequently isolated together with other non-fermentative, gram-negative rods from clinical specimens. We report an isolate of S. maltophilia showing an oxidase-positive reaction, which is very rare for the species. (Korean J Clin Microbiol 2008;11:132-135)