Mycobacterium gordonae was isolated as a light growth from bronchoalveolar aspirates from nine patients over 12 months. All patients were in one hospital, and had been bronchoscoped for suspected malignancy. None of the patients had symptoms or radiographic findings of mycobacterial infection. The isolates were characterized by biochemical tests and molecular hybridization. Random amplified polymorphic DNA analysis (RAPD) was used to test whether the strains had a common origin. All the isolates generated four to eight fragments, and almost all presented distinct RAPD patterns. Antimicrobial resistance patterns to six agents confirmed that the isolates were unrelated. Thus epidemiologically unrelated strains of M. gordonae can exist as contaminants in the same department over a relatively short time frame. RAPD analysis is easy to perform, gives rapid results, and can be used for epidemiological analysis of M. gordonae isolates.