Background: Venous thromboembolism is a multifactorial disease that depends on a variety of acquired and genetic risk factors. Pulmonary embolism is usually considered to be a complication of deep
vein thrombosis. Therefore the genetic risk factors for both entities are believed to be the same.Case Report: We present the case of a 40-year-old man from northwestern Greece ,initially admitted to Hospital because of lobar pneumonia.Seven days later,he developed deep vein thrombosis soon followed by pulmonary embolism. He was heterozygous for the G1691A mutation in the Factor V gene, for the G20210A mutation in the prothrombin gene and exhibited decreased activity of the protein S.Conclusions: The genetic predisposition and the severity of his clinical course were seriously considered in order to decide that the oral anticoagulation treatment should be continued indefinitely.

Keywords: factor V Leiden, prothrombin mutation, thromboembolism, Pulmonary Embolism