Purpose. - Despite appropriate therapy 10 to 100% of patients with deep vein thrombosis (DVT) of the lower limbs will develop post-thrombotic syndrome (PTS). The aim of this study was to evaluate the incidence of PTS in the EDITH cohort and to estimate the association between initial patients' characteristics and the risk of development of PTS. Methods. - One hundred and eighty patients included in the EDITH study for a first event of DVT of the lower limbs without clinical signs of venous insufficiency were recalled 4 years after their initial thrombotic event. PTS was diagnosed according to the Villalta score. Results. - Ninety-five patients (45 men, mean age 50.7±16.9 years) were evaluated for PTS. Among them, 28.4% (95% CI 19.3-37.5) developed PTS but none had severe PTS. The most frequent clinical signs of PTS were varicose veins (59%), corona phlebectatica (48%), swelling leg (30%) and pigmented dermatitis (26%). No single risk factor was associated with PTS development (age, sex, BMI thrombophilia, etiology, localization, recurrence, symptomatic DVT and familial history of DVT). Conclusion. - PTS is a frequent disease. However, lack of uniformity of diagnosis criteria in the different studies does not make possible the estimation of PTS risk factors.