The sympathetic nervous system occupies a prominent role in heart failure both as a marker of severity of disease and also as an important factor in its progression. Beta blocker therapy, once thought heretical in heart failure, has consistently improved cardiac function and slowed progression of disease. Large clinical trials of mild to moderate heart failure show improved survival as well as reduction in hospitalization. Beta blockers now have stronger data in heart failure than converting enzyme inhibitors, and should be considered standard therapy in mild-moderate heart failure. Ongoing trials are addressing beta blocker therapy in advanced heart failure and comparisons between agents.