Cardiac involvement in AL-amyloidosis due to a multiple myeloma is present in up to 90% of cases. We present two patients with cardiac symptoms in whom a hematologic disease could be diagnosed because of suspicious cardiac finding. The leading symptom was dyspnea. The routinely performed laboratory tests, especially the erythrocyte sedimentation rate and the electrophoresis, were normal. After exclusion of coronary artery disease an infiltrative cardiomyopathy was suspected because of the echocardiographic examination with marked left ventricular hypertrophy, the restrictive flow pattern at the mitral valve and the electrocardiogram with a low voltage in limb leads and absent R waves in left precordial leads. Further, hematologic workup confirmed the production of light chains due to a myeloma. If the echocardiographic examination and the electrocardiogram raises the suspicion of an infiltrative cardiomyopathy as the cause of dyspnea, an immunofixation should be done in spite of normal laboratory tests to confirm or rule out the presence of a light chain disease due to a myeloma.