Suicidal behavior is a clinically significant but underestimated cause of mortality in narcissistic personality disorder. Currently, there are no reliable estimates of suicidal behavior for this population. The main objective of this study was to test whether or not suicide attempters diagnosed with narcissistic personality disorder are different in terms of impulsivity and expected lethality from suicide attempters with other cluster B personality disorders. In a sample of 446 suicide attempters, patients with cluster B personality disorder diagnoses (n = 254) as assessed by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), version of the International Personality Disorder Examination-Screening Questionnaire (IPDE-SQ) were compared in terms of expected lethality and impulsivity (measured by the Beck Suicidal Intent Scale and the Barratt Impulsiveness Scale, respectively). The subjects were admitted to the emergency departments of the Ramón y Cajal Hospital and the Fundación Jiménez Diaz University Hospital in Madrid, Spain, between January 1999 and January 2003. Suicide attempts of subjects diagnosed with narcissistic personality disorder had higher expected lethality than those of subjects without narcissistic personality disorder (t = -4.24, df = 439, P < .001). There were no differences in expected lethality of the attempts when comparing subjects with and without histrionic personality disorder (t = 0.28, df = 439, P = .795), antisocial personality disorder (t = 0.66, df = 439, P = .504), and borderline personality disorder (t = 1.13, df = 439, P = .256), respectively. Suicide attempters diagnosed with narcissistic personality disorder did not significantly differ from suicide attempters without narcissistic personality disorder in terms of impulsivity measures (t = -0.33, df = 442, P = .738), while suicide attempters diagnosed with antisocial personality disorder, histrionic personality disorder, and borderline personality disorder were significantly more impulsive than suicide attempters without these diagnoses (t = -3.96, df = 442, P < .001; t = -3.88, df = 442, P < .001; and t = -7.44, df = 442, P < .001, respectively). Narcissistic personality disorder seems to be a distinct group among cluster B personality disorders with regard to suicidal behavior. In contrast to suicide attempters with other cluster B personality disorders, suicide attempters diagnosed with narcissistic personality disorder are less impulsive and have suicide attempts characterized by higher lethality. These distinctions may offer a basis for targeted therapies aimed at decreasing suicidal risk in patients with narcissistic personality disorder.