Liquid silicone is an inert material that is utilized for cosmetic procedures by physicians as well as illegally by nonmedical personnel. We present a case report and collated clinical findings of 32 other patients who were hospitalized after illegal silicone injections. Symptoms and signs of the "silicone syndrome" included dyspnea, fever, cough, hemoptysis, chest pain, hypoxia, alveolar hemorrhage, and altered consciousness. Bilateral patchy alveolar infiltrates were present on the chest radiographs, and silicone pulmonary emboli were detected in all the patients. The patients could be divided into two groups based on the initial presentation and clinical outcome. Twenty-seven patients in group 1 presented predominantly with respiratory symptoms, and 93% of patients were discharged home within 3 weeks. Six patients (group 2) presented with severe neurologic findings, and experienced rapid deterioration and 100% mortality. The clinical findings after silicone embolism are very similar to the published reports of fat embolism, including hypoxemia in 92% of patients with silicone embolism (patients with fat embolism, 56 to 96%), dyspnea in 88% of patients (patients with fat embolism, 56 to 75%), fever in 70% of patients (patients with fat embolism, 23 to 67%), alveolar hemorrhage in 64% of patients (patients with fat embolism, 66%), neurologic symptoms in 33% of patients (patients with fat embolism, 22 to 86%), petechiae in 18% of patients (patients with fat embolism, 20 to 50%), chest pain in 15% of patients (patients with fat embolism, 26%), and mortality in 24% of patients (patients with fat embolism, 5 to 20%). The similarities among the mode of injury to the lung, the clinical findings, and the high incidence of alveolar hemorrhage suggest a common pathogenesis of silicone and fat embolism syndromes. We discuss the possibility that the activation of the coagulation system may be important in the development of these clinical syndromes.