Three new cases of thromboembolic accidents involving the superior vena cave were associated with ovarian hyperstimulation and multiple pregnancy. On the basis of a review of the literature, three syndromes were individualized. First embolic arteries are infrequent and serious with an important morbidity; low doses of gonadotrophines is sufficient for causing this pathology. Second, thrombosis of the superior vena cava is late, during in vitro fertilization regimens with GnRH analogs complicated with serious hyperstimulation (degree III). Third, pregnancy is always present; pulmonary complications are very uncommon. Thrombosis of inferior vena cava is late, pregnancy is often present but women are frequently at risk of thromboembolic accident. Prevention of hyperstimulation is important. When present, HBPM is recommended for prevention of thromboembolism. Diagnostic of thrombosis is made with clinical examination and morphologic complementary exams such colour-vascular Doppler and magnetic resonance imaging. Curative treatment requires heparinization.