Influenza A (H1N1) caused its first pandemic in 2009 in USA and Mexico. Since then, clinicians have exercised great care in order to make an early diagnosis of viral pneumonias. This is due in part to pandemic influenza A infection having greater impact on populations <65 years old than other viral strains, including seasonal influenza. Chest radiographies of those affected displayed a rapid progression of patchy infiltrates, and a large proportion of individuals required admission to intensive care units (ICU). Despite efforts, patients infected with the virus had a high mortality rate. The present multicenter study aimed to retrospectively evaluate the clinical, demographic and prognostic characteristics of patients diagnosed with epidemic viral pneumonia in Turkey. A total of 92 patients were included in the study. The Student's t-test and Chi-square tests were performed to analyze quantitative data, assuming a normal distribution, and to analyze qualitative data, respectively. Stepwise logistic regression was used to evaluate the effects of demographic variables and laboratory values on the virus mortality rate. The male/female ratio was 42/50 and the mean age was 48.74 +/- 16.65 years. A total of 69 (75%) patients were unvaccinated against influenza. The most common symptoms were cough (87%) and fever (63%). Chest computed tomography showed peripheral patchy areas of the lungs of ground glass density in 38 patients (41.3%). A total of 22 (59.4%) patients had H1N1, 5 (12.5%) patients had influenza B, and 38 (41.3%) patients met the criteria for admission to the ICU. Of these patients, 20 (52.63%) were monitored with a mechanical ventilator, with a noninvasive ventilator being adequate for 10 (26.32%) of patients. The length of stay in the ICU was 6.45 +/- 5.97 days and the duration of mechanical ventilation was 5.06 +/- 4.69 days. A total of 12 (13.04%) patients in the ICU succumbed. Logistic regression analysis revealed that among the parameters possibly associated with mortality, being an active smoker increased the risk of mortality 7.08-fold compared to other groups (P=0.005). In conclusion, viral pneumonia remains a significant health problem during the winter period. Considering the high number of ICU admissions and high rate of mortality for patients in the present study, earlier initiation of antiviral therapy is necessary. Active smoking increased mortality in viral pneumonia.