The aim of this study was to examine the prescription of psychotropic medication for patients with a primary diagnosis of personality disorder (PD) detained at Rampton High Secure Hospital, compared with that for patients with a primary diagnosis of mental illness. The name and the dose of psychotropic medication prescribed for each patient in the sample, on 2 July 2010, were examined. Although nearly all patients with a primary diagnosis of mental illness were prescribed psychotropic medication (98%), the percentage within the Personality Disorder (73%) and the Dangerous and Severe Personality Disorder services (62%) was also high, with the most commonly prescribed drug being an antipsychotic in all groups. The dose of antipsychotic and mood-stabilizing medication was lower for patients with a primary diagnosis of PD, and clozapine was the antipsychotic of choice for a significant proportion of these patients. Medication may have a key role to play in the management of some groups of patients with PD.