Anaerobes are important causes of pleural space infections. The aim of the study is to evaluate the role of the anaerobic bacteria in pleural infections. The study involved 278 consecutive clinical samples sent to the Clinical Microbiology Laboratory of Tertiary Chest Hospital. Anaerobes were isolated in 39 community acquired and five nosocomial cases out of 278 anaerobic cultivations (15.8%). Total of 56 anaerobe strains were identified and 21 aerobes were accompanied to anaerobic isolates. Aerobe isolates were associated with anaerobic microorganisms in 19 cases (43.2%). Bacteroides species (21.4%) and Pseudomonas aeruginosa (33.3%) were the most common anaerobic and aerobic isolates.