A prospective study of community-acquired pneumonia in adults at Srinagarind Hospital, Khon kaen University was conducted from September 1987 to August 1988. Laboratory specimens were tested for bacterial and mycoplasmal culture, CIE for pneumococcal antigen and serological data for mycoplasma and P. pseudomallei. The results supported by clinical data were evaluated. We could identify the pathogens from 62 of 113 cases (55%). P. pseudomallei was the most frequent etiologic agent (32%) and S. pneumoniae was the second (27%). Overall mortality was 21 per cent and it was high in cases with bacteremia and pneumonia due to P. pseudomallei. Sixty-six per cent of the patients had associated diseases. Diabetes mellitus, chronic renal failure and renal calculi were commonly found in patients with pneumonia due to P. pseudomallei. The results of this study showed the relatively high prevalence of P. pseudomallei pneumonia in our region which was different from other reports.