A 57-year-old woman who had been operated on for colon cancer and given chemotherapy, presented in September 1995 with worsening cough and abnormalities on her chest X-ray film. Acid-fast bacilli were isolated from the sputum. The organism was classified as M. gordonae by biochemical tests and DNA/DNA hybridization. The patient was treated with rifampicin and clarithromycin. Subsequently, sputum cultures became negative and the chest x-ray film showed a decrease infiltration. The findings in the present case suggest that M. gordonae may cause pulmonary infection and should be considered as an opportunistic pathogen.