Objective To examine pre‐treatment characteristics associated with dropout in 224 adolescent psychiatric inpatients (mean age 17.1 years) with severe disruptive behaviour. To date, little is known about the factors predicting dropout among adolescents treated for severe disruptive behaviour. This is surprising, as dropout is a major problem in this specific group. Method Dropouts (n = 77) and completers (n = 147) were compared on known risk factors for dropout, such as severity of externalising problems and disorders, ethnic minority status, male gender, and lower academic functioning, as well as on other factors considered relevant: behavioural characteristics, including age of onset and different types of disruptive behaviour. Within dropout, withdrawal (termination against the advice of the therapist; n = 40) and pushout (termination against the wish of the client; n = 37) were distinguished. Results Two characteristics significantly predicted dropout: early onset of disruptive behaviour and cannabis usage prior to treatment. Within the dropout group no differences were found between withdrawals and pushouts. Conclusions Predicting dropout among adolescent psychiatric inpatients with severe disruptive behaviour is difficult. The two predictors found were already present at the time of admission and are therefore considered unalterable. However, they can be used to pinpoint individuals with higher chance at dropout, who in turn can be offered tailored interventions aimed at improving the therapeutic relationship.