Summary. In patients with malignant tumour signs and symptoms develop that cannot be explained on the basis of the mass effect produced by either primary tumour or its metastases, production of a hormone associated with tissue type giving rise to the malignant tumour, or patieets’ immune status. These symptom complexes are known as paraneoplastic syndrome. It is known that the patients with malignant tumours are prone to dvelop venous thromboembolism in any stage of their disease. It is suggested that thromboembolic manifestations in cancer patients may be part of the secondary antiphospholipid syndrome (APS) and an example of the paraneoplastic autoimmunity, eg., paraneoplastic syndrome. Antiphospholipid antibodies (APA), e.g., anticardiolipin antibodies (ACA) and circulating lupus anticoagulant (LAC) are known to predispose to venous and arte- rial thromboses. The growing number of clinical reports on the association of APA and malignant tumours suggests that APA may be one of contributory factors in the paraneoplastic thromboembolism occurring in malignancy.