Deep venous thrombosis is common problem in hospitalized patients. Thrombosis of deep vein begins in calf and extends proximally. The various risk factors has been identified for DVT, and usually presence of more than one risk factors are required. Well’s scoring system stratifies patients into low, moderate and high risk categories. Other scoring system are also used in clinical practise, however none of them have been widely validated. The test performed for the diagnosis of DVT includes: D dimer assay, plethysmography, compression ultrasonography, Doppler ultrasound and venography. Further, certain tests are performed to determine the underlying abnormality and increased risk of recurrence. D-dimer value is proportional to the extent of DVT, size of clot and its surface area. D-dimer assay may also have role in predicting recurrences. Thrombophilia testing is not indicated routinely. However, when indicated it should not be performed before 6 weeks.