Venous thromboembolism is an uncommon complication after thoracic surgery. However, it is a dangerous complication because it is often overlooked due to its infrequent and silent symptoms. The study is carried out to determine the rate and risk factors of venous thrombosis in patients who experienced thoracic surgery by applying adjusted Caprini risk assessement model. This study using descriptive cross section design was conducted on 35,612 patients undergoing thoracic surgery from 1/2017 to 12/2018. All patients were assessed for risk prior to surgery and supervised for 30 days postoperatively. The results showed that the rate of venous thromboembolism after 30-day thoracic surgery was calculated as 0.22% (78/35612). The risk of developing postoperative venous thromembolism in patients with a total caprini score of 7-8 points was estimated as 7.13 times which is higher than that of patients in the group with Caprini score 0-2. The risk factors increasing the likelihood of postoperative venous thromboembolism include: Age, sex, peripheral vascular disease, varicose cein, diabetes and especially history of thrombosis