Increasingly, it is recognized that significant ventricular dysfunction can exist in the absence of symptoms for an extended period of time in patients with cardiovascular disease. Recent multicenter trials have demonstrated that therapy during the asymptomatic phase can reduce progression to symptomatic heart failure and mortality. Little is known about the epidemiology of this problem. However, preliminary studies suggest that the prevalence of asymptomatic left ventricular dysfunction may approach that of clinically apparent congestive heart failure. The mechanisms whereby some patients with severe ventricular dysfunction may remain asymptomatic while others with similar degrees of ventricular dysfunction have severe symptoms of heart failure remain unclear. By understanding these mechanisms, we may devise novel therapies which will prolong the asymptomatic phase and hopefully prevent the progression to heart failure. This review focuses on pertinent clinical and pathophysiologic issues pertaining to asymptomatic left ventricular dysfunction.