Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are important aetiologies of community-acquired pneumonia (CAP). The rapid laboratory diagnosis of CAP is difficult by conventional culture techniques. Polymerase chain reaction (PCR) is an advanced tool, which may solve this problem. Sputum samples were selected and scored by Gram stain. Conventional identification procedures and PCR analysis were applied to the samples and results were compared statistically. Ranging between the ages of 20-80, 107 patients with suspected bacterial pneumonia admitted to the department of The Chest Diseases of Gulhane Military Medical Academy were included in this study. Sixty-seven of 107 (62.6%) samples were positive in PCR, but only 11 in culture. Streptococcus pneumoniae (40.2%; 43/107) was the most common etiologic agent in PCR. The incidences of H. influenzae and M. catarrhalis were determined as 11.2% (12/107), and 1.9% (2/107), respectively in PCR. Oropharyngeal contamination could be a cause of the false positive results in PCR. If valid sputum were to be obtained, PCR might be more sensitive, reliable and beneficial than culture.