Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen. We investigated MRSA-infections in patients with pulmonary diseases referring to epidemiological aspects. Between 9/92 and 2/92 we found MRSA-infections in our hospital in 24 patients (11 female, 13 male, average age 54.6 years). Clinical presentation, main and accompanying disorders and previous antibiotic therapy regimens were registered. Strains were typed using DNA-RFLP and lysotyping. MRSA detection were done in specimen from sputum (12/24) and from the bronchial secret (9/24). In 18/24 cases the MRSA-colonisation was associated with infection. In 15/24 cases the first acquisition of MRSA happened in our hospital, 6/24 times the germ was carried off other institutions and in 3/24 cases it was possibly community acquired. Most frequently patients suffered from bronchial cancer (6/24), from chronical bronchitis (5/24), from pneumonia (4/24) or Cystic fibrosis (4/24). Usually the patients showed other severe comorbidity. 13/24 patients had an antibiotic course before detecting MRSA. Typing revealed a strain already known in different hospitals of Berlin, another known strain of northern Germany and two so far unknown strains. Of interest was a different behaviour of resistance and the lost of resistance of strains in the course. MRSA-infection in pulmonary medicine emerged as a problem mostly in patients with multimorbidity and severe underlying diseases. Change of resistance in strains and new strains were observed.