About a quarter of the psychiatrists at the Maudsley Hospital use the diagnosis of 'borderline' personality. The description of the borderline patient obtained in this study does not overlap with any existing ICD personality disorder but has characteristics of the schizoid, paranoid, hysteric, explosive, anankastic and antisocial personalities. The item that discriminated best between borderlines and controls was 'brief, unsystematized , psychotic episodes', which is not included in the DSM-III definitions of borderline diagnoses. Items of the DSM-III 'schizotypal' set--e.g. 'suspiciousness' and 'ideas of reference'--discriminated better between borderline cases and controls, whereas items of the DSM-III 'borderline personality' set--e.g. 'impulsivity' or 'unpredictability'--scored more frequently in both groups. These are similar to American findings.