49 year‑old patient with multiple myeloma diagnosed a year earlier, after a few cycles of chemotherapy was admitted to hospital with heart failure symptoms accompanied by a rapid atrial flutter. Echocardiography revealed eccentric hypertrophy of the left ventricle and reduced ejection fraction approx. 20% and non sustained ventricular tachycardia episodes in the Holter ECG. Due to the gradually deteriorating patient’s condition electrical cardioversion was performed restoring sinus rhythm. Applied pharmacological treatment brought relief of symptoms reported at admission. To clarify the etiology of heart failure coronary angiography was performed excluding the presence of coronary artery disease. Because of the frequent occurrence of amyloidosis in patients with multiple myeloma, the amyloid cardiomyopathy was suspected and the investigation in that direction was started. Histology samples of abdominal fat and gums mucous in a hematoxylin and eosin and Sirius red staining showed no signs of amyloidosis. However, bone marrow biopsy revealed the presence of protein corresponding to the extracellular amyloid deposits. The patient died a few months later in hematology clinic due to severe multiple organ failure associated with generalized amyloidosis. JRCD 2015; 2 (2): 22–25