Senile cardiac amyloidosis has been considered an incidental finding at autopsy in the elderly and of little clinical importance. Autopsy studies have shown that a subset of this group have large deposits of amyloid in their ventricles. Many of these patients had congestive heart failure antemortem. Senile cardiac amyloidosis, however, is rarely diagnosed antemortem and is often confused with primary systemic amyloidosis involving the myocardium. Using endomyocardial biopsy with newly developed immunohistochemical techniques, we have been able to recognize senile cardiac amyloidosis premortem. We have found that these patients have a longer survival than patients with primary systemic amyloidosis. In addition, senile cardiac amyloidosis occurs at a younger age than autopsy studies suggest. Recognition is important because these patients should not be given treatment reserved for the therapy of primary cardiac amyloidosis.