In this research the mechanical properties of short and long term of poly(ether ether ketone) (PEEK) and nanohydroxyapatite (nHA) nanocomposites with potential application as orthopedic implants were studied. The nHA was surface-treated with the coupling agent amino-ethyl-amino-propyl-trimethoxysilane (AEAPTS). After treatment, the nanoparticles (pure and treated) were mixed with the PEEK in a twin screw extruder. Subsequently, specimens of both type of nanocomposites were injection molded and thermal treated (annealed) to increase crystallinity. The neat PEEK was processed at the same conditions. The nanocomposites samples had their short term (tensile and impact) and long term (fatigue) mechanical properties measured. From the tensile tests, it was found that the ultimate tensile strength of the silane treated nanocomposite decreased with its silanization; however, the stress and strain at break increased. The presence of the silane also increased the fatigue life of the nanocomposite suggesting that a higher interaction between the matrix and the nanofiller occurred. The impact tests confirmed the higher impact strength of the sample with silanized nHA.The annealed samples showed that the presence of the silane did not modify significantly the mechanical behavior of the material. Keywords: silane; nanocomposite; fatigue; PEEK; nanohydroxyapatite