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