The homeless mentally disordered defendant facing minor charges poses considerable problems regarding appropriate disposal. Psychiatric assessment may be required in order to facilitate the court's decision, but this is often available only after remand in custody. A psychiatric assessment service based at two inner-London magistrates' courts is described. Over 18 months, 201 defendants were referred. They were predominantly male, single, and of no fixed abode, suffering from serious psychiatric disorder; these defendants had often received previous in-patient treatment, frequently as detained patients. They typically were recidivists charged with minor offences. Following initial assessment, 25% were admitted to hospital, 50% were released, and 25% returned to custody. The Crown Prosecution Service discontinued 29% of cases. For those admitted directly to hospital, the mean (s.d.) time from arrest to hospital admission was 5.8 (6.8) days, significantly quicker than with prison-based assessments.