In 111 patients with left ventricular ejection fraction < or =30% who required hospitalization for heart failure, we examined the association between outpatient dose of diuretic agents and all-cause mortality. In comparison to patients who were not on treatment with diuretics prior to hospitalization, patients being treated with 'low' doses of diuretics (<80 mg/day of furosemide) and those being treated with 'high' doses of diuretics (> or =80 mg/day of furosemide) were more likely to die during follow-up after adjustment for other clinical parameters (adjusted relative risks, RR, 3.1 and 4.6).