BACKGROUND AND OBJECTIVES: A high level of coagulant factor VIII is a well known risk factor for venous thromboembolism, but most studies have enrolled patients under 70 years old. This study aimed to test the hypothesis that an association also exists in the elderly. DESIGN AND METHODS: This hospital-based case-referent study took place at the Department of Internal Medicine and Chest Diseases, University Hospital, Brest, France. We enrolled 161 patients with a first episode of venous thrombosis and 239 subjects, referred for a clinical suspicion of venous thromboembolism which was subsequently ruled out. Factor VIII coagulant activity and plasma fibrinogen concentration were measured. RESULTS: High factor VIII coagulant activity was significantly associated with venous thromboembolism, irrespective of the age group. Patients over 70 years with factor VIII coagulant activity above 225% had a 2.4-fold increased risk of venous thromboembolism compared to those patients with levels below 130% (age- and fibrinogen-adjusted odds ratio: 2.6, 95% CI 1.1 to 6.1). INTERPRETATION AND CONCLUSIONS: Our results show that high levels of factor VIII coagulant, a determinant of venous thrombosis in adulthood, is also a risk factor in the elderly.