BACKGROUND AND OBJECTIVE: The aim of the study was to describe the effects of influenza associated with community-acquired pneumonia (CAP) on the outcome of patients in an area characterized by endemic avian influenza. METHODS: Sixty patients diagnosed with CAP and requiring hospitalization were studied for the presence of influenza. Based on the presence or absence of influenza, patients were divided into two groups: group 1 were CAP patients positive for influenza and group 2 included CAP patients negative for influenza. Laboratory investigations, CXR findings and prognosis were compared. RESULTS: Nasopharyngeal swabs or deep tracheal aspirates were tested for viral aetiology, and seven patients were positive for influenza AH3; one was positive for influenza AH1; seven were positive for influenza B; and one was positive for parainfluenza. Group 1 patients (n = 16) had a mean age of 56 years and group 2 patients (n = 45) had a mean age of 55 years. Significant increases in creatinine kinase and lymphopaenia were seen in group 1 patients. On CXR, interstitial infiltration was more marked in group 1. There was significantly higher mortality in group 1 than in group 2. CONCLUSION: CAP associated with influenza had a different clinical picture and outcome compared with patients without evidence of influenza.