Background: Prognostic implications of diuretics dose are not completely understood. We aim to study the association between diuretic doses and long-term prognosis in patients with chronic stable heart failure (HF). Methods and Results: We conducted a retrospective cohort study of 244 patients followed at an outpatient HF clinic. Admission criteria were clinical stability in the previous 3 months and optimized medical therapy. Demographic characteristics, clinical, and laboratory parameters were recorded. Patients were followed for 2 years and the outcome was defined as all-cause death or hospital admission due to HF worsening. Patients on ≤80 mg furosemide were compared with those on higher doses. Patients were grouped according to furosemide dose (≤80 mg and >80 mg/d) and according to volemia as assessed by the sodium retention score: <3 (euvolemia) versus ≥3 (hypervolemia). Patients on higher diuretic doses (n = 79) were older, more hypervolemic, and more symptomatic. Patients on >80 mg furosemide had a higher risk of death or hospital admission (hazard ratio [HR]: 2.07, 95% confidence interval [CI]: 1.37-3.1). For each 40-mg furosemide tablet, there was a 67% increase in risk of an adverse outcome within 2 years. The increase in risk was independent of other variables crudely associated with prognosis. Among euvolemic patients, those on ≤80 mg/d furosemide performed better than those on higher doses. Among hypervolemic patients, the diuretic dose had no prognostic implications. Conclusions: Higher diuretic doses associated strongly and independently with adverse long-term outcome in chronic HF. Possibly, in euvolemic patients, efforts should be made to reduce diuretic dose.