The authors assess the mortality from the neuroleptic malignant syndrome (NMS) based on an exhaustive review of 202 published case reports, including a differential assessment of risk factors and protective factors. The results indicate a significant (p less than .05) decrease in mortality since 1984 (11.6% vs. 25% before 1984), which occurs independently of the therapeutic use of dopamine agonists and dantrolene. A significantly (p less than .001) lower rate of mortality from haloperidol-induced NMS (7%) and a high rate of mortality (38.5%) among patients with organic brain syndrome were also found. Myoglobinemia and renal failure are strong predictors of mortality, representing a mortality risk of approximately 50%. The authors discuss the implications of these findings.