The relationship of self-mutilation to suicidal behavior was studied in 108 borderline inpatients (defined by the Diagnostic Interview for Borderline Patients). Patients with histories of selfmutilation were compared to those with no self-mutilation on diagnostic comorbidity, symptom patterns, prior suicidal be haviors, and attempt characteristics, including number of at tempts, seriousness of intent, and medical lethality.Self-mutilation was found in 63% of patients, suicidal attempts in 75.7%. Patients with self-mutilation were significantly younger and more symptomatic than controls, and had more serious suicidal ideation and recent suicide attempts. On the DIB they had significantly more manipulative suicide threat or effort, depersonalization and drug-free hallucinations or delu sions. They tended toward more depression and schizotypal symptoms but less anger and assaultiveness compared to nonmutilating patients. Histories of manipulative suicide attempts were characteristic of self mutilating patients; however, self mutilation was not associated with increased seriousness of in tent or lethality of suicide attempts.Self-mutilation is a common clinical phenomenon, with a reported inci dence of 3.4-7.7% among general psychiatric admissions (Ballinger, 1971;Pao, 1969). Etiology is often described as "multifactorial," with psychologi cal, behavioral, and biologic determinants, though generally related to the disorder in which the symptom arises. The most bizarre and destructive acts arise from the thought disorder of the psychotic patient, including autocastration, enucleation, and amputations. The least severe acts, de scribed as syndromes of "wrist slashing," "delicate cutting," or "parasuicide," are generally attributed to personality-disordered patients, especially those with borderline personality disorder (BPD) (Grunebaum &