¹Kalp Damar Cerrahisi AD, İnönü Üniversitesi Tıp Fakültesi, Malatya DOI : 10.9739/uvcd.2012-32287 Objective: In this study, we aimed to investigate incidence of Factor V Leiden mutation in patients with deep vein thrombosis. Material and Methods: Between January 2009 and August 2011, 53 patients with deep vein thrombosis were investigated for Factor V Leiden mutation. Of all, 50.94% patients were males and age range was 19-83 years. All of the patients were hospitalized. Standard IV heparine and warfarine were administered. Screening tests for etiology were done for all patients. Results: Eleven patients were heterozygotes (7 males, 4 females) (20.75%), 2 patients were homozygotes (2 females) (%3.77). Pulmonary embolism was evident in 1 heterozygote female patient. Of 6 patients with recurrent deep vein thrombosis, 1 heterozygote male and 1 homozygote female patients were detected. One of the patients with reccurent deep vein thrombosis was a patient in the 6th decade and had malignancy. Deep vein thrombosis occured due to risk factors such as immobilisation, pregnancy, postpartum period or maligancy in 6 patients. Femoral veins were involved in all patients with factor V leiden mutation. Conclusion: Life time oral anticoagulation therapy is inevitable in patients with Factor 5 leiden mutation especially with recurrent deep vein thrombosis. Additionally; screening tests for family members must be considered. In patients with high risk, genetic consultation is important for prophylaxis of deep vein thrombosis and preparation for medical emergencies. Keywords : Factor V leiden; thromboembolism; deep venous thrombosis; prophylaxis