The purpose of this study was to investigate treatment decision in a population of psychiatric patients referred with suicide attempt to medical emergency room in a large community hospital. A distinct scope of the study was to assess the impact of a quality assurance program on the adherence of the psychiatric staff to a system of diagnostic and treatment decision guidelines. After a preliminary field trial of patient flow and treatment assignment at emergency room discharge over 1-month, we implemented a consensual diagnostic and treatment decision manual. Then, an educational program aimed to improve the understanding of the reliability of treatment decision among the psychiatric staff of the emergency room. In short, a substantial proportion of psychiatric patients with suicide attempt did not receive adequate treatment assignment at discharge and the presence of a clinical diagnosis of borderline personality disorder was a factor of even more unpredictable treatment choice. This is an issue of great need and potential impact since medical decisions often appeared to favour either treatment that are more expensive or treatments that are at increased risk of completed suicide. Further steps of the data analyses aimed to clarify the impact of better quality assurance on the reliability of treatment decision are under scrutiny and will be discussed.