The selection of patients for heart transplantation involves the use of multiple prognostic variables. Because of the complexity of the clinical syndrome of heart failure, central cardiac and peripheral maladaptations occur. Exercise capacity simultaneously assesses cardiovascular reserve and evaluates the peripheral maladaptations; accordingly, exercise testing has become an increasingly important tool in the risk stratification of these patients. Established prognostic indicators in heart failure are reviewed. The role exercise testing plays in selecting ambulatory patients for heart transplantation is emphasized.