After long bone fractures, as well as hip or knee total arthroplasty, the increase in intramedullary pressure induces bone marrow release into the circulation in more than 90% of patients. Three to four percent of the patients reveal fat embolism syndrome with pulmonary and cerebral involvement and a petechial rash. In about 20% of these patients a fulminant and fatal course is possible. Although fat embolism syndrome was described more than a century ago, there is still no sufficient therapeutic strategy. Because of these facts we try to prevent fat embolism syndrome and monitor patients at risk perioperatively. We have evaluated different diagnostic methods and monitoring facilities and recommend pulse oximetry, capnography, ECG, blood pressure controls and, if indicated, blood gas analyses for perioperative monitoring. Patients at risk and patients who are suffering from fat embolism syndrome require more intensive monitoring, such as transesophageal echocardiography and a pulmonary artery catheter to obtain more detailed information about the hemodynamic and oximetric variables. Furthermore, these patients must be admitted to an intensive care unit.