Background: Neonatal intensive care units are prone to a variety of errors due to their special conditions. Failure mode and effects analysis (FMEA) is a method for risk assessment and management, which assesses the safety of patient care processes through its system approach. Objectives: The present study aimed to identify and assess common medical errors at Amirkola Children’s hospital NICU in 2016. Methods: This was a cross-sectional study conducted from September 2015 to February 2016 in the NICU of Amirkola Children’s Hospital in the city of Babol to identify and assess the medical errors and their effects qualitatively and quantitatively using FMEA through direct observations of the NICU processes, brainstorming, and focus group discussions (FGD). The FMEA standard worksheet was used for data collection. The collected data were analyzed using Excel 2010. Results: In this study, 4 key processes were selected through studying the care methods and brainstorming including drug administration, infection control, medical equipment use, and laboratory tests; 27 activities and 50 potential failure modes, as well as their impacts were detected and recorded in the final worksheet of FMEA. According to the calculated PRNs, 27 potential failure modes with PRN > 65 were determined as high-risk failures. The highest and lowest PRNs were, respectively, related to improper and incomplete washing and disinfecting the hands (PRN = 127) and illegibility of the lab requests for laboratory tests (PRN = 32). Conclusions: Based on the findings of this study, 57 potential failure modes in 4 key processes of the studied NICU were determined, among which 27 potential errors and failures with high risks were recognized. Therefore, it can be suggested that the senior managers and administrators should create multidisciplinary teams for patient safety at the organizational and unit levels