Abstract： Objective The purpose of our study was to evaluate the prevalence of deep venous thrombosis(DVT) in suspected pulmonary embolism patients. Methods From January 2004 to June 2006,all patients who underwent CT pulmonary angiography combined with lower extremity CT venography or lower extremity sonography were consecutively enrolled in 2 hospitals. The prevalence of deep venous thrombosis in suspected pulmonary embolism patients and the location of DVT were analyzed. The statistical analyses were performed with the SPSS 11.5 statistical software, frequency analysis was performed for discriptive results and chi-square analysis was performed for comparison between groups. Results Three hundred and thirtyseven consecutive patients were enrolled. There were 189 men and 148 women. The median age was 62 (range from 19 to 84 years old). Pulmonary embolism were diagnosed by CT pulmonary angiography in 144 patients, and DVT was diagnosed by CT venography or lower extremity sonography in 100 patients. The prevalence of DVT in pulmonary embolism patients was 44%, and 76% DVT was located in proximal lowe rextremity veins. The prevalence of pulmonary embolism in DVT patients was 63%. Conclusion The prevalence of DVT in patients with pulmonary embolism and the prevalence of pulmonary embolism in patients with DVT are both high(44% vs 63%) ; therefore it is necessary to examine the pulmonary arteries and the lower extremity deep veins at the same time.