Deep venous thrombosis (DVT) or pulmonary embolism may occur in almost 2 in 1000 people each year, with up to 25% of those having a recurrence. Around 5% to 15% of people with untreated DVT may die from pulmonary embolism. Risk factors for DVT include immobility, surgery (particularly orthopaedic), malignancy, pregnancy, older age, and inherited or acquired prothrombotic clotting disorders.We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for proximal DVT? What are the effects of treatments for isolated calf DVT? What are the effects of treatments for pulmonary embolism? What are the effects of interventions on oral anticoagulation management in people with thromboembolism? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found 45 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticoagulation; compression stockings; low molecular weight heparin (short and long term, once or twice daily, and home treatment); oral anticoagulants (short and long term, high intensity, abrupt discontinuation, and computerised decision support); prolonged duration of anticoagulation; thrombolysis; vena cava filters; and warfarin.