The size, quantity and shape of total hip replacement wear debris may identify wear mechanisms as well as play a role in osteolysis. Characterization of wear particles generated from a hip joint simulator was conducted followed by comparison with literature reported in vivo results. The effect of counterface material and lubricant type on particle morphology was assessed. Biomaterial pairs including UHMWPE articulated against CoCr, Alumina and Zirconia were considered. Deionized (D.I.) water and bovine serum were used as lubricants. Particles generated from Alumina/UHMWPE in serum were slightly larger than those for CoCr and Zirconia against UHMWPE in serum. Particle shape for these materials in serum were similar, with two types including a round or egg shaped submicron one and an elongated fibrous 1-2 micron one. Particles from CoCr against UHMWPE in D.I. water were flake like in shape and in the millimeter size range with some in the 5 micron range as well. The water condition produced particles dissimilar to the others. Literature reported clinical findings supported the particle types and sizes generated under serum while those generated in water were not supported in the literature. The in vitro simulator was found to accurately reproduce in vivo wear mechanisms under serum lubrication based on debris characterization results.