Primary amyloid light chain (AL) amyloidosis of the heart is a rare cause of congestive heart failure. Approximately 15% of patients with primary AL amyloidosis demonstrate no monoclonal proteins on serum or urine immunoelectrophoresis:(so-called nonsecretory immunoglobulin-derived amyloidosis). The histologic findings of endomyocardial biopsy from these patients may be indistinguishable from those with senile cardiac amyloidosis. However, the AL type may respond favourably to chemotherapy while the latter type does not. The prognosis is also better in the senile cardiac amyloid type. The precise diagnosis in the present case was made by applying immunohistochemical techniques on cardiac tissues.