The aim of this study was to determine the incidence of iatrogenic events in the tertiary NICU of Cairo university hospitals, so we performed a prospective, observational cohort study for all patients admitted in a 6 months period from June 2012 to December 2012. A total of 202 patients we studied during 3350 patient days. We recorded 259 iatrogenic events in 116 patients. The incidence rate was 7.8 iatrogenic events per 100 hospitalization days, while the prevalence rate was 57.4 infants with iatrogenic events per 100 hospitalized infants. The average of iatrogenic events was 2.2 per patient. We had 44 severe events that affected the outcome of the patients, affecting 37.9% of the patients who suffered IEs, while the fatal events were 19 (16.4%).