Deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, causing disruption or complete occlusion of blood flow. People who require lower limb immobilisation – for example after an injury such as metatarsal fracture, Achilles tendon rupture or malleolar fracture – are at increased risk of DVT, since epithelial injury and stasis will be present. Various patient-related and admission-related risk factors can further increase the risk of DVT. It is crucial that patients are individually assessed to determine their risk of DVT and their need for pharmacological thromboprophylaxis. This article discusses the indications for lower limb immobilisation, the mechanisms by which lower limb immobilisation creates a risk of DVT and the individual risk factors that compound the risk of thrombosis. It also outlines the importance of individualised risk assessments, the methods of pharmacological thromboprophylaxis and the nurse’s role in providing patient education.