Patients with cancer have an increased risk of venous thromboembolism (VTE). There is evidence that the absolute risk of VTE in cancer patients depends on the type of cancer, stage of disease, treatment with chemotherapy, hormone therapy, immunomodulatory drugs (IMiDs), surgical procedures, the presence of an indwelling central venous catheter (CVC), age, immobilisation and length of anaesthesia. In these patients, risk factors may interact. In addition, cancer patients are at higher risk of recurrent VTE and bleeding than patients without cancer. Thrombotic complications have a significant impact on morbidity and, in some cases, also on mortality of patients with cancer; therefore, thromboprophylaxis to prevent VTE is needed. In some patients, venous thromboembolism may be the earliest symptom of an occult neoplasm. Furthermore, many patients who received a diagnosis of cancer within a year of VTE, already had distant metastases at the time of cancer diagnosis. The literature about the relation between cancer and venous thromboembolism was reviewed, with particular attention to risk factors of VTE in oncological patients, and connections between VTE and diagnosis of occult malignancy. Next, the prevention and treatment of venous thromboembolism in cancer patients is discussed. Finally, a potential anti-tumour and antimetastatic effect of anticoagulation and prognosis of these patients is described. Identifying high risk patients and the application of suitable prevention is the best way to reduce the incidence of VTE and its associated complications.