Leg length discrepancy may occur following total hip arthroplasty, with a potentially impaired functional outcome as a result. The aim of this study was to compare the leg length discrepancy between both cemented and uncemented femoral stems when used in total hip arthroplasty. A prospective radiological study of 200 consecutive primary total hip arthroplasties was performed between June 2005 and December 2006. Pre and post-operative radiographs were analysed. 56 (56%) of the total hip arthroplasties where an uncemented femoral stem was used had a leg length discrepancy over 1 cm. However only 23 (23%) of the total hip arthroplasties with a cemented femoral stem had a leg length discrepancy over 1 cm. The use of cemented femoral stems in total hip arthroplasty results in a lower incidence of leg length discrepancy, with a potentially better functional outcome.