Venous thrombo-embolism (VTE) has been recognised as a leading cause of morbidity and mortality in the acute spinal cord injury (SCI) population. It is thought that deep vein thrombosis (DVT), the most common form of VTE will occur in the majority of patients in the absence of adequate prophylaxis in the SCI group. Pulmonary embolism, which is often preceded by a DVT, is a leading cause of death in the first year after injury for this group of patients. The reliability of signs and symptoms in the diagnosis of thrombo-embolism has been debated in medicine since the 1960s; however diagnosis of DVT remains problematic. The most commonly used of these signs and symptoms in the SCI patient group is swelling of the calves and/or thighs as indicated by an increase in a daily circumference measurement. After a review of the literature it was identified that there were several aspects of reliability of the current practice of lower limb circumference measurements that had been poorly examined including the location the measurements are performed, the landmarks used to determine the location to be measured, the type of tape measure being used and the inter-rater reliability of the procedure. The aim of this study was to test the reliability of calf and thigh circumference measurements by testing the stability and equivalence of the equipment, the procedure and the measurements. This three phase prospective study was designed to determine how much the Birch tape measure stretches over time, if the standard (Birch) tape measure can be used instead of the Gulick spring tape for circumference measures, at which measurement location could the most consistent measurements be produced and whether it was possible for staff to consistently reproduce measurements over time.