Obesity is a known risk factor for venous and arterial thrombosis but the mechanisms are still unclear. In women, obesity is correlated with low-grade inflammation and recent data show that BMI is positively associated with thrombin generation. We explored the correlations between obesity, inflammation and thrombin generation in women with increased thrombotic risk by looking at a cohort of women with prior venous thrombosis. One hundred and fifty-six women age 18-65 years were enrolled at diagnosis of first venous thromboembolism (VTE). Plasma samples were obtained at least 3 weeks after cessation of anticoagulant treatment. Thrombin generation was determined with the calibrated automated thrombography (CAT) assay and the Innovance ETP assay. Thrombin generation started later but was more pronounced with higher endogenous thrombin generation potential (ETP) determined with CAT in patients with obesity. The Innovance ETP assay showed results consistent with CAT. Furthermore, patients with obesity had significantly higher levels of fibrinogen, C-reactive protein and plasminogen activator inhibitor-I (PAI-I) than patients without obesity. Increased levels of fibrinogen were the main determinant of the prolonged lag-time in patients with obesity whereas higher levels of prothrombin could account for the difference in the ETP between the groups. We found an association between BMI and ETP values using two different methods to measure thrombin generation. Obesity correlated with increased thrombin generation in women with VTE and the main determinants of this hypercoagulable state were increased levels of fibrinogen and prothrombin. This shows a possible link between obesity, low-grade inflammation and increased thrombin generation in women at increased risk for future thrombosis.