Abstract: UHMWPE is a semi-crystalline polymer which used as a acetabular cup in total hip joint replacement with some failure for a long time, therefore in this research, we attempted to improve tensile properties of UHMWPE polymer by addition of CNTs and nHA with four weight fractions (1, 2, 3 and 5%) to produce nanocomposites. The measured properties included tensile strength, modulus of elasticity and elongation percentage. All the results indicated enhancing the properties, especially for UHMWPE/3% CNTs and UHMWPE/5% nHA. FE-SEM examination was done for specimens at the fracture region to identify the structure of nanocomposites that confirm the good cross linking between the matrix and reinforcements.