Fillers, in the form of particulates and fibers, are often added to polymeric materials to improve their stiffness and strength. Polymers and their composites are being increasingly employed in view of their good strengths and low densities.' Besides, a wider choice of materials and ease of manufacturing make them ideal for engineering applications. High density polyethylene filled with particulate fillers is of great interest in both research and industry. It is well known that HOPE has good process ability allowing accepting different types of natural and synthetic fillers. As fillers, mica, kaolin, calcium carbonate and talc are the most often used to reduce both the production cost and to improve the properties of the thermoplastics, such as rigidity, strength, hardness, flexural modulus, dimensional stability, crystallinity, electrical and thermal conductivity. In the present work, high density polyethylene based composites filled with glass spheres, talc and calcite particles were prepared. Fillers contents in the HOPE were 5, 10, 15, and 20 wt%. HOPE composites filled with glass spheres, talc and calcium carbonate were prepared using extrusion compounding and injection molding. The effects of filler contents on the mechanical, morphological and thermal properties of the polymer composites were studied. The modulus of elasticity, yield and tensile strength, % elongation, izod notched Impact strength, Shore D hardness, MFI, HDT and Vicat softening point of the composites were determined. The structure and properties of the composites are characterized using a scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).