Pliable and bioactive composites made of hydroxyapatite (HAP) and ethylene vinyl acetate (EVA) copolymer were developed for the repair of defective cranium. This article describes the mechanical properties of HAP-EVA composites. The effects of HAP particle size and morphology of HAP on the properties of resultant composites were investigated using various techniques. It was found that the composites containing smaller HAP particles had higher values of tensile modulus, flexural modulus, and impact strength. Examination of the fracture surfaces revealed that only a mechanical bond existed between the filler and the matrix. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1594-1601, 2011