The mechanical and setting properties of calcium phosphate cements are considerably determined by the pretreatment of the constituents. In this report we show for the first time that prolonged high-energy ball milling of a-tricalcium phosphate (alpha-TCP) led to mechanically induced phase transformation from the crystalline to the amorphous state. The amorphous material demonstrated a high reactivity such that the time for substantially complete conversion of a-TCP to calcium-deficient hydroxyapatite in 2.5 % Na2HPO4 solution decreased from about 20 h (1 h of grinding in ethanol, 85% relative crystallinity) to 4-6 h for a material with a crystallinity of 8% (24 h of grinding). This reactivity could be attributed to an increased thermodynamic and kinetic solubility of the ground materials. Mechanically activated a-TCP cements were produced with compressive strengths of up to 80 MPa and setting times of 5-16 min. The effect of reactant preparation and cement mixing parameters on the physical and chemical properties of mechanically activated a-TCP cement was investigated. By comparing cements of similar porosity and degree of conversion it was demonstrated that apatite specific surface area has a strong influence on cement mechanical performance, which highlights the importance of this previously overlooked parameter in improving strength.