The incidence and clinical significance of pulmonary embolism (PE) in pulmonary malignancy were analysed among 111 autopsy cases including: 65 primary and 24 metastatic lung cancer, 8 hematological malignancies and 14-malignant pleural mesothelioma. In 34 (31%) cases PE was found, in 4 (12%) patients cancer tissue emboli was documented. In nonsmall cell lung cancer the frequency of PE was 40%, compared to 24% in small cell, 25% in metastatic lung cancer and 14% in mesothelioma. Deep venous thrombosis of lower extremities was the source of thrombotic material in 35% cases. In remaining cases the sources of thrombotic material were different (caval vein inferior, superior, and their main branches, right heart cavities, pulmonary artery). In 8 patients with PE the acute form of DIC was observed. In 15 (44%) patients the clinical ante mortem diagnosis of PE was done. In 26% of all analysed cases PE was the direct cause of death. We concluded that PE is a frequent and dangerous complication of lung neoplasms. Clinical diagnosis can be extremely difficult.