OBJECTIVE: This exploratory study sought demographic and clinical correlates of self-mutilation (self-injury without suicidal intent) in borderline personality disorder. METHOD: Among 124 consecutively admitted inpatients with borderline personality disorder, there were 62 who did not mutilate themselves, 23 who mutilated themselves infrequently (fewer than five lifetime events), and 39 who mutilated themselves frequently (five or more lifetime events); each received ratings on numerous measures of psychopathology. RESULTS: Compared to nonmutilators, frequent mutilators were significantly more likely to be in outpatient treatment at the time of admission and had more weeks of prior outpatient and inpatient treatment; they were also more likely to receive comorbid diagnoses of current major depression, anorexia nervosa, and bulimia nervosa. Frequent mutilators had significantly higher group means on the Beck Scale for Suicidal Ideation, were more likely to have attempted suicide, and were more likely to have attempted suicide more often than both infrequent mutilators and nonmutilators. The adjusted odds ratios from logistic regression analyses demonstrated that major depression, bulimia nervosa, number of prior suicide attempts, and acute suicidal ideation were each associated with greater risk of frequent mutilation. CONCLUSIONS: Borderline patients who frequently mutilate themselves may represent a subgroup of especially high utilizers of psychiatric treatment who are at particularly high risk for suicidal behavior and for comorbid major depression and eating disorders. Clinicians should consider aggressive treatment of comorbid axis I disorders and careful assessment of suicide risk in these patients.