An in-patient behavioural psychotherapy unit is described that emphasises self-treatment, teaching relatives to become cotherapists while resident in the unit, routine collection of outcome data, minimising use of medication, and absence of night nurses. Patients are referred from all over the UK, mostly with chronic disabling OCD. Treatment includes self-exposure and self-imposed response prevention. A year's cohort (52 patients) showed substantial improvement that consolidated during six-month follow-up (83% decrease in total ritual time per day, 58% fall in target ritual scores, better social adjustment), and families noted relief of burden; eight patients dropped out. Further such units are needed in the UK, perhaps on a regional basis; they could be run as specialist hostels.