Clozapine (Clozaril®, Sandoz, East Hanover, NJ), an atypical antipsychotic agent with pharmacological properties considerably different from standard neuroleptics, has been found to be of great benefit especially to patients with treatment-resistant psychotic disorders. However, it is these unique pharmacological properties that have also been associated with mul tiple side effects ranging from the relatively benign (ie, sialorrhea during sleep, dizziness) to the potentially fatal (ie, agranulocytosis, seizures, and respiratory depression) which have limited its use. These untoward side effects are particularly problematic in the elderly population who often have concomitant medi cal illnesses requiring multiple medication regimens, including psychotropics that may interact with cloza pine (ie, benzodiazepines, cimetidine, fluoxetine). Because even the most benign of side effects has the potential of becoming fatal in certain circumstances if left unaddressed, it is imperative for patients, clinicians, pharmacists, and all health care professionals to be aware of adverse reactions and possible complica tions of clozapine therapy to prevent significant morbidity and mortality. Copyright © 1996 by W.B. Saunders Company