Newer atypical antipsychotics demonstrate superior effectiveness, with a diminished incidence of extrapyramidal side effects compared with older typical antipsychotics, but they have been associated with the development of obesity and new-onset diabetes. A small number of reports documenting modest hypertriglyceridemia related to newer antipsychotics have implicated fluperlapine, clozapine, and, most recently, olanzapine. This study summarizes the results of 14 cases of severe hypertriglyceridemia (>600 mg/dL) associated with olanzapine and quetiapine therapy occurring among inpatients at Oregon State Hospital, including 7 patients whose serum triglyceride levels exceeded 1,000 mg/ dL. Four of these patients also developed new-onset diabetes. Nine cases occurred during the first 8 months of treatment, with three cases identified within 3 months of commencing olanzapine or quetiapine therapy. Weight gain in olanzapine and quetiapine groups was modest (12.3 lb and 8.5 lb, respectively) and did not correlate with the severity of hypertriglyceridemia. Biochemical causes for severe hypertriglyceridemia associated with novel antipsychotics are unclear, but clinical monitoring of serum lipids must be added to the concerns about the metabolic consequences of therapy with certain newer antipsychotic agents.