Fat embolism, which is an important type of non-trombotic embolism, is generally seen as a complication of long bone trauma. It presents with respiratory, circulatory, neurological system symptoms. This multisystemic diseases may end with mortality. A 27-year-old man referred to our hospital with confusion, dyspnea and fever. His complaints started after a long leg cast applied because of a right tibia fracture 36 hours ago. Chest radiograph showed bilateral reticulonodular densities His arterial blood gases measurement revealed hypoxemia and hypocapnia. There was no pulmonary embolism shown in thorax CT angiography, as demonstrating bilateral diffuse infiltrations. Fat embolism was thought in differential diagnosis with a clinical presentation of acute respiratory disease syndrome (ARDS).