Purpose: Determine the relationship between the severity of heart failure and.the incidence of Deep Venous Thrombosis (DVT) of the lower limbs in patients hospitalized with chronic heart failure. Materials and method: Descriptive, cross sectional and prospective study. Since April, 2011 to March, 2013, there were 136 patients treated in Nhan Dan Gia Dinh Hospital, HCMC were diagnosed as chronic heart failure grade III, IV according to New York Heart Association Functional Classification (NYHAFC). Research by using Doppler,. ultrasound the lower limbs' veins from the ankles to the inguinal folds in both legs. Results: The incidence of DVT of the lower limbs of patients with chronic heart failure grade III, IV by NYHA-FC is 42.6 percent (58/136 patients). Heart failure patients classified as NYHA IV have a higher incidence of DVT (NYHA III: 31.3 percent, NYHA IV: 70 percent, p=0.0001). Multiple logistic regression analysis identified the NYHA IV functional class as an independent predictor of DVT (OR 4.51, 95 percent CI 1.86-10.94, p=0.001). Conclusion: Patients with heart failure have a high risk for DVT and the risk increases according to NYHA III/IV functional class.