RESULTS: Most prescriptions were handwritten (45.7%). In 47.0% of handwritten, mixed and pre-typed prescriptions had patient name errors; the prescriber name was difficult to identify in 33.7%; 19.3% of them were hardly legible or illegible. Of a total of 7,148 high-alert drugs prescribed, 3,177 errors were found, and the most frequent one was missing information (86.5%). Errors occurred mostly in prescriptions of heparin, phentanyl, and midazolam. Intensive care and neurology units had the highest number of errors per prescription. Non-standard abbreviations were frequent and widespread. Overall it was estimated 3.3 errors per prescription order form. Pre-typed prescriptions were less likely to have errors compared to mixed or handwritten prescriptions.