This study tested the efficacy and safety of aerobic exercise training in patients with chronic heart failure (n=2,331) followed for 2.5 years. Exercise training resulted in nonsignificant reductions of all-cause mortality or all-cause hospitalization and in secondary clinical endpoints (all-cause mortality, the composite of cardiovascular mortality or cardiovascular hospitalization and the composite of cardiovascular mortality or heart failure hospitalization). However, after adjusting for highly prognostic predictors of the primary endpoint, exercise training was associated with modest but significant reductions for both all-cause mortality or hospitalization and cardiovascular mortality or heart failure hospitalization.