INTRODUCTIONThe merit of using D-dimer estimations in patients following total hip and knee replacement has been previously questioned. A survey of radiology protocols in 70 hospitals ascertained that the test continues to be mandatory in 51 prior to formal radiological investigation of suspected deep vein thrombosis (DVT) in this patient population.PATIENTS AND METHODS In this study, D-dimer levels were measured pre-operatively and during the first 7 days following primary total hip and knee replacement to estimate the range of normal values in these patients. RESULTS All 78 patients were ultrasonographically shown to be clear of DVT. D-Dimer levels were significantly raised in all patients at all measurements during the first week. Levels after total knee replacement were higher than after total hip replacement. Comparison was made with an age-matched group who had a proven DVT. There was no difference in D-dimer levels between patients with or without a DVT. CONCLUSIONS The use of this test in this patient group is a waste of resource and merely delays appropriate radiological investigation and treatment.