The fat embolism syndrome is clinically evident in approximately 0.5-2.0% of patients with long bone fractures. The clinical signs and symptoms are evident in 60% of patients within 24 hours and 85% of patients within 48 hours after trauma. A patient is reported who complained of dyspnea and hemoptysis approximately 72 hours after sustaining a fracture to the distal tibia and fibula. Radionuclide ventilation/perfusion imaging was obtained to rule out pulmonary thromboemboli. Perfusion imaging demonstrated the characteristic diffuse, subsegmental ("mottled") appearance of fatty emboli to the lung.