Fourteen young adults treated for obsessive-compulsive disorder in adolescence, mainly though not only by behaviour therapy and family therapy, were followed up between nine and 14 years later. This is the longest follow-up period so far reported for obsessive-compulsive disorder treated in adolescence. Case histories show remarkable variability and unpredictability. Clinical implications include that a crucial focus for long-term care should be the effective management of relapse, that intensive behaviour therapy during adolescence may obviate the need for long-term maintenance pharmacotherapy and that the disorder should be treated vigorously at any stage with guarded optimism, notwithstanding previous treatment history.