The goal of this study was to examine the perceived usefulness and the perceived ease of use of a Hospital Information System (HIS) for the care staff. We administrated a questionnaire composed of open-end and closed questions. As results, the perceived usefulness and ease of use are correlated with medical occupations. Content analysis of open questions highlights three factors influencing these constructs: ergonomics, errors in the documenting process and insufficient compatibility with the medical department or the occupation. While the results are consistent with literature, they show medical occupations do not report the same low rate of perceived usefulness and of ease of use. The main explanation consists in the medical risk in the prescription process for anesthesiologists, surgeons and physicians.