Hip joint implants are one of the most delicate areas of arthroplasty, due to their vulnerability, proneness to injury & the variety of loads they bear. The implant plastic liner which separates the femoral head & a femoral stem, is mostly made of ultra high molecular weight polyethylene (UHMWPE). Although the polymer is known for its chemical stability & appropriate mechanical strength, there are still some drawbacks such as low hardness, wear resistance & large wear debris. In this regard, wear debris which would result in osteolysis & implant failure, is becoming one of the most emerging subjects in biomaterials design. One of the most promising ways to overcome the obstacle is adding different particles to the UHMWPE matrix. In this study,different contents of zirconia & graphene nanoplatelets were added separately to the UHMWPE-10 wt.% HAp matrix using solvent mixing & ultrasonication followed by hot press. Pin-on-disk test & vickers microhardness were carried out to obtain coefficients of friction, wear rates & hardness of the samples. MTT assay & Cell adhesion test were also performed to evaluate biocompatibility & surface structure of the samples using MG-63 osteoblast cells. The result indicated that 65% & 92% reduction in COF & wear rate for the sample containing 10 wt.% zirconia, respectively. While the same parameters were reduced by 54% & 53% in the sample containing 0.5 wt.% GNP, as a result of GNP restacking & clustering at high contents which led to failure of the sample containing 1.5 wt.% GNP. Microhardness was also increased by 65% for the same zirconia containing sample, while it only increased by 34% in the case if GNP addition. Biological tests proved that all the samples were safe for in vitro application with almost more than 90% cell viability in 7 days during the MTT assay. Likewise, cell morphology exhibited fully spread cells & complete coverage of zirconia containing samples which is an indicator of zirconia osseoconductivity properties. At the same time, the presence of pseudopods & insufficinet attachment on the surface of GNP containing samples, approved that despite the absence of cytotoxicity, GNP flakes might not be the best solution when cell adherence is essential. Consequently, the results proved that zirconia might bring up a new horizon in the field of modifying liners made of UHMWPE due to its significant effect on improving both wear & biological behavior of the implants matrix.