INTRODUCTION: DVT or pulmonary embolism may occur in almost 2 in 1000 people each year, with up to 25% of those having a recurrence. Around 5-15% of people with untreated DVT may die from pulmonary embolism. Risk factors for deep vein thrombosis include immobility, surgery (particularly orthopaedic), malignancy, pregnancy, older age, and inherited or acquired prothrombotic clotting disorders.METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for: proximal deep vein thrombosis; isolated calf deep vein thrombosis; and pulmonary embolism? What are the effects of computerised decision support on oral anticoagulation management? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2007 (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).RESULTS: We found 40 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.CONCLUSIONS: 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, home treatment), oral anticoagulants (short and long term, high intensity, abrupt discontinuation, computerised decision support), prolonged duration of anticoagulation, thrombolysis, vena cava filters, and warfarin.