Few previous studies have evaluated the relationship between nosocomial infection and mortality in a neurology intensive care unit (ICU). In this study, patients treated for more than 24h in the neurology ICU of the Ankara Training and Research Hospital, Turkey were followed until death or two days after discharge by prospective daily surveillance. The study period was 14 months. One hundred and sixty-nine ICU-acquired infections occurred in 74 (38.9%) of 190 patients during 2006 patient-days. The overall rate of ICU-acquired nosocomial infection was 88.9/100 patients and 84.2/1000 patient-days. While the overall mortality rate was 60%, mortality in patients with nosocomial infections was 69%. In univariate analysis, infection (nosocomial and community-acquired) (P=0.002), nosocomial infection (P<0.05), mechanical ventilation (P<0.0001), presence of two or more underlying diseases (P=0.01), parenteral nutrition (P<0.0001), steroid treatment (P=0.003) and a low Glasgow Coma Scale (GCS) score (P=0.0001) were identified as risk factors for mortality. Stepwise logistic regression analysis showed nosocomial infection (P<0.05), mechanical ventilation (P=0.009), the presence of two or more underlying diseases (P<0.05) and a low GCS score (P=0.0001) to be risk factors for ICU mortality. It was concluded that nosocomial infection increases the risk of mortality by a factor of 1.69. The impact of nosocomial infection on mortality in our ICU was higher in patients with high GCS scores and patients aged between 66 and 75 years. In particular, nosocomial infection increased mortality among patients with less severe illnesses.