According to the Swiss legal system, involuntary admission is one of the farthest-reaching incursions into personal autonomy. The effect of compulsory admission in treatment of substance use disorders (SUDs) on variables such as length of stay or leaving treatment before recommended discharge remains elusive. In order to elucidate these effects, we retrospectively analysed the clinical course of treatment of 608 patients who were admitted between November 2016 and October 2017 to the Department of Addictive Disorders of the canton of Aargau.