Seclusion with or without restraint is a measure used to manage patients with challenging behaviours. Although controversial, the intervention remains poorly documented, especially in Canadian psychiatric hospitals. The purpose of this study is to assess the prevalence of the measure and identify any correlated demographic characteristics and psychiatric disorders. Episodes of seclusion with or without restraint were extracted from a computerized, hospital-based system introduced specifically to track such interventions. Of 2721 patients hospitalized during that time, 23.2% (n = 632) were secluded with or without restraint, and 17.5% (n = 476) were secluded with restraint. Younger age, schizophrenia or other psychosis, bipolar and personality disorder, and longer stay in hospital are predictors of an episode of seclusion with or without restraint. Younger age, bipolar and personality disorders and a longer stay in hospital are predictors of an episode of seclusion with restraint. For patients who spent longer in seclusion and under restraint, there is a positive association with longer stay in hospital. In this inpatient psychiatric facility, seclusion with or without restraint thus appears to be common. More research is warranted to better identify the principal factors associated with seclusion and restraint and help reduce resort to these measures.