Therapists are only now just beginning to clear a way through the jungle of personality disorder and any recommendations about drug treatment have to be tentative and, to some extent, speculative. Nevertheless, it is reasonable to conclude that drug treatment, mainly in the form of antipsychotic agents, should be considered in borderline and antisocial personality disorders and also possibly in the schizotypal group. There is also growing evidence that two drugs used in the treatment of manic-depressive psychosis, lithium and carbamazepine, may have independent effects in controlling aggression and impulsiveness and be of value of borderline and antisocial personality disorders. In histrionic and dependent personality disorders, drug treatment is in general contraindicated and for the remaining group our ignorance of the possible benefit of the drugs is almost total. However, the negative effect of these personality disorders on response to treatment in the presence of depression, anxiety, and other abnormal mental state disorders suggests that drug treatment probably has little part to play in management of these particular personality disorders. A major deficiency in our knowledge, which can only be remedied by long-term studies that are extremely difficult to mount, is the recommended duration of treatment with drugs in personality disorder. No guidelines exist at present but now that some measure of efficacy has been established duration of treatment needs to be addressed.