We investigated the relationship between resting heart rate (HR) and two measures of beta-1 receptor sensitivity/blockade: (1) the percentage of maximal predicted heart rate reached during exercise (%MPHR), and (2) the HR increase per unit of circulating norepinephrine (NE) or the chronotropic responsiveness index (CRI) in 28 patients with systolic CHF on chronic beta-blocker therapy. Our results show that resting HR is not associated with HR response during exercise nor with beta-1 receptor sensitivity to circulating NE.