Background: Elastic compression stockings (ECS) are uncomfortable to wear but may prevent post-thrombotic syndrome (PTS). The ability to predict PTS may help clinical decision making regarding the optimal duration of ECS after deep vein thrombosis (DVT). Aims: Predefined endpoint analysis of the Octavia study that randomized patients who compliantly used ECS up to one year after DVT to continue or discontinue ECS treatment. Primary aim was to identify predictors of PTS. Methods: Patient characteristics were collected and ultrasonography was performed to assess reflux, residual thrombosis and persistent thrombus load 12 months after DVT. Multivariable analyses were performed to identify factors related to PTS. Results: Thrombus score ≥ 3, BMI ≥ 26, duration of symptoms before DVT diagnosis ≥ 8 days and a Villalta score of 2–4 points were statistically significant predictors of PTS. The predictive value for PTS for the assessed variables was not different between the 2 treatment groups. In the stop ECS group, 3.2% (95%CI 0.08–18) of patients without any predictors for PTS were diagnosed with mild PTS during follow-up, and none with severe PTS, for a sensitivity of 98% (95% CI 89–100), a specificity of 14% (95% CI 10–20), a positive predictive value of 20% (95% CI 19–22), and a negative predictive value of 97% (95% CI 81–100). Conclusion: We identified 4 predictors of PTS occurring in the 2nd year after DVT. Our findings may be used to decide on whether to continue ECS treatment for an additional year, after one year of compliant ECS use, keeping in mind that patients with none of the predictors will have the lowest PTS incidence.