Background: Australia is committed to reduce or eliminate the use of containment measures (seclusion and restraint) in mental health care. International research suggests that number of containment events and hours spent in containment are often concentrated in a small number of patients. Understanding the concentration of containment episodes can support the development of effective interventions. Objectives: The purpose of this study is to explore the distribution and frequency of seclusion and restraint events and hours in adult inpatient mental health units in South Australia. Design: A retrospective audit of seclusion and restraint events during the time period 1/1/2010-31/12/2011. Setting: Eighteen (18) inpatient mental health units in South Australia. Results: Containment events were concentrated among a relatively small proportion of patients (10% of patients accounting for nearly 40% of events), with the concentration even more evident for containment hours (10% of patients accounting for over 50% of hours). Rates of containment varied widely between units. The highest rates were in high dependency units, which also accounted for over 90% of patients with the highest percentage of events and hours. More males than females experienced containment, with a significantly larger proportion of males experiencing the highest number of hours in containment. Conclusions: The concentration of containment events supports the validity of tailoring interventions, such as structured short-term risk assessment tools, reviewing repeat events and debriefing, to high-risk cases. These strategies should be used in conjunction with hospital-wide strategies with demonstrated efficacy, for example leadership, education, consumer involvement and data analysis.