Background: The risk of venous thromboembolism (VTE), defined as deep vein thrombosis, pulmonany embolism (PE), or both, in myotonic dystrophy (DM) is unknown. Our objective was to estimate the risk of VTE in DM and its impact on all-cause and cardiovascular mortality. Methods: In 1,148 retrospectively studied adults (592 women) suffering from DM, referred between January 2000 and January 2015, we estimated the cumulative incidence of VTE and proportion of all- cause and cardiovascular deaths, and compared the incidence of VTE with that in patients with other inherited myopathies followed at our center, and with a community-based French population. Results: Among all patients with DM (mean age=40.6#14.3; 592 women), 82 developed VTE over a 10.9-year follow-up (95% CI 2.4 to 14.7), representing a 10.3% cumulative incidence (95% CI 7.8 to 12.7%), and 253 died, 83 of a cardiovascular cause. In patients with DM, the incidence of VTE was higher than a) in 1,662 patients (mean age=39.7+16.2; 989 women) with other inherited myopathies (mean age=39.7+16.2), in whom the cumulative incidence was 2.2% (95% Cl 1.1 to 3.3) and hazard ratio (HR) 4.63 (95% CI 2.63 to 8.18; p<0.0001), and b) in a community-based population with a standardized rate ratio of 7.53 (95% CI 6.02 to 9.28; p<0.0001). VTE was independently predicted by age (HR=1.02; 95% CI 1.00 to 1.04; p=0.041), personal history of VTE (HR=4.71; 95% CI 2.20 to 10.1; p<0.0001), obesity (HR=2.31; 95% CI 1.30 to 4.08; p=0.004), loss of ambulation (HR=4.57;95% C| 2.12 to9.87; p=0.0001) and history of cancer (HR=3.89; 95% CI 1.62 to 9.32; p=0.002). The 26 deaths from PE in patients with DM represented 10.3% of all deaths and 31.3% of cardiovascular deaths. Conclusion: The risk of fatal and non-fatal VTE in patients with DM was high.