BACKGROUND Fat embolism syndrome is a well-known complication in orthopedic and trauma surgery, caused by a massive release of fat into the circulation that can lead to cardiopulmonary insufficiency and multiorgan failure. CASE REPORT We present the case of a 72-year-old man with osteoarthritis who underwent an elective right cementless total hip arthroplasty. Two hours after surgery, the patient lost consciousness and was found hypotensive and with reduced oxygen saturation, with a severe right heart dilatation at echocardiographic evaluation. Death occurred after cardiopulmonary resuscitation attempts. Post-mortem microscopic examination revealed that the final cause of death was pulmonary fat embolism associated with coronary amyloidosis and atherosclerosis. CONCLUSIONS This case called our attention on the sudden onset of fat embolism syndrome after arthroplasty and the insidious nature of amyloidosis infiltrative disease. The autopsy findings substantially aided understanding the immediate cause of death.