Background: Although error could be present in almost every medical practice, they are more frequent and potentially more dangerous in neonatal intensive care units (NICU). Objective: To determine prescription error rate of intravenous drugs in a Neonatal Intensive Care Unit (NICU), and to describe type of error (dose, dilution, and interval) and medication (antibiotics, inotropics, or analgesics).Methods: Observational study including medical records of patients hospitalized in a NICU, receiving any of the above mentioned drugs. Each prescription was compared with one provided by a specific software. Prescription error was defined as >10% of difference between both values.Results: 362 prescriptions from 82 patients were analyzed. An error was observed in 42.5% (95%CI 37.4 – 47.8) of all prescriptions, including 148 (96.1%; 95%CI: 91.3-98.4) antibiotics prescriptions, 5 (3.2%; 95%CI: 1.2-7.7) inotropics prescriptions and 1 (0.7%; 95%CI: 0.01-4.2) analgesics prescriptions. Prescription errors were due to frequency error in 53.8% 95%CI: 45.6-61.8 of cases and to volume error in 46.1% (95%CI: 38.1-54.3). Conclusion: Almost half of the intravenous drugs prescriptions included an error, being more frequently related to interval, followed by dosing; no errors in dilution were detected. Using prescription software could improve patient’s safety.