Klinefelter’s syndrome, characterized by a karyotype of XXY, is characterized by a series of clinical manifestation such as hypogonadism, small testes, gynecomastia and infertility. This condition promotes hypofribrinolysis due to hormonal imbalances and thrombophillic factors resulting in a hypercoagulability state. Rare complications include thromboembolic events and deep vein thrombosis. Here is a typical case of a 51-year-old man diagnosed with Klinefelter’s syndrome after being admitted and treated for pulmonary embolism.