Hydroxyapatite reinforced high density polyethylene composite (HAPEX™) has been developed for bone substitution. To improve its mechanical properties, HAPEX™ was hydrostatically extruded at different extrusion ratios after compression moulding. Substantial increases in the tensile and flexural properties of both unfilled polyethylene and HAPEX™ were achieved. It was evident that the higher the extrusion ratio, the stiffer and the stronger the extruded rods. The ductility of HAPEX™ was also significantly enhanced by hydrostatic extrusion. Hydrostatically extruded HAPEX™ possesses mechanical properties that are within the bounds for human cortical bone, which indicates its potential for load-bearing skeletal implant applications.