Nosocomial infections are an important cause of preventable morbidity and mortality; they also result in significant socioeconomic cost. Nosocomial pneumonia (NCP) is defined as pneumonia, which occurs 48 hours after hospitalization or after discharge from the hospital. It is the second or third most frequent infection among all hospital acquired infections, and the mortality of NCP is higher than the other hospital acquired infections. Patients, diagnosed as NCP were retrospectively analyzed in order to detect microbiological agent and prognostic factors. We evaluated 173 patients, 67.0% of them were male and 33.0% female. Comorbid diseases were present in 94.2% and a medical procedure had been applied in 75.1% of cases. A single agent was isolated in 79.2% of the cases while a mixt infection was present in 13.3%. In 7.5% of the cases, cultures were negative. Endotracheal aspirates were the most common materials (38.9%) used for detected microorganism and sputum cultures were used in 16.8% of the cases. Most commonly encountered microorganism were Pseudomonas aeruginosa, Acinetobacter spp. and Staphylococcus aureus respectively. NCP developed on approximately 18th day of hospitalization. Overall mortality rate was 45.2%. The effects of diabetes mellitus and chronic pulmonary diseases on mortality rate were analized by logistic regression analysis and it's evaluated that the mortality rates increase 3.7 times with diabetes mellitus and 2.4 times with chronic pulmonary diseases. There was no effect of mechanical ventilation history on mortality.