Beta-blockers (BBs) are mandatory therapy for patients with systolic chronic heart failure (CHF). However, it is uncertain whether target dose of these agents is more important than the achievement of target heart rate (HR) in maximizing the benefits of these agents. To test this, we obtained ECG absolute HR from patients with systolic CHF, together with consecutive left ventricular ejection fraction (EF) measures at least 3 months apart. Patients were divided into those who achieved target dose for beta-blocker and/or target absolute HR of < or = 60 beats per minute (bpm) and target change in HR (>10 bpm reduction) with increasing dose. Baseline ejection fraction (EF) was similar across all groups. Patients with absolute or change in HR at target achieved a greater change in EF than those not at target (P= 0.027 and P= 0.012, respectively). In contrast, those who achieved target dose did not achieve a significantly greater improvement in EF than those not at target dose (P= 0.81). Similarly for absolute EF, patients at target HR or target change in HR achieved a greater EF increase than those achieving target dose. Based on these data, target HR or change in HR appears to be more critical to improvement in EF than target dose in CHF patients. Therefore, achieving an absolute HR or change in HR with BBs may be more important than target dose in maximizing benefits of BBs in this setting.