Aims and method To evaluate whether involuntary out-patient commitment (OPC) in patients with severe mental disorder reduces their use of hospital services. This is a retrospective case-control study comparing a group of patients on OPC (n = 75) and a control group (n = 75) which was composed of patients whose sociodemographic variables and clinical characteristics were similar to those of the OPC group. Each control case is paired with an OPC case, so the control case must have an involuntary admission in the month that the index OPC case admission occurred. Emergency room visits, admissions and average length of hospital stay over a 2-year follow-up after the initiation of OPC were compared. Results No statistically significant evidence was found in the use of mental healthcare services between the two groups. Different reasons for admission found between the groups limit similarity when comparing the two. Clinical implications The findings cast doubt over the effectiveness of this legal measure to reduce emergency visits, the number of admissions and the length of stay in the hospital.