The occurrence of neoplasms in patients with idiopathic deep vein thrombosis (DVT) may result in a significant reduction in survival rates. The aim of our study was to assess the use of chest X-rays (CXRs) as a screening method of intrathoracic neoplasms in patients who with idiopathic DVT. In observational, cross-sectional study, the medical records of 99 patients with idiopathic DVT, who were submitted to CXR (during the hospital stay or within 30 days after discharge), were investigated. Of these patients, 15.1% had images suggestive of thoracic neoplasias (single or multiple pulmonary nodules and mediastinal widening). Neoplasms were diagnosed in 4 patients in the follow-up with CXR. The CXR is an option of early screening for thoracic neoplasms and other nonmalignant diseases in patients with idiopathic DVT.