A size-controllable synthesis of hollow structures of apatite in the hexane-water-bis(2-ethylhexyl) sulfosuccinate is presented, and the hollow sphere sizes can be easily regulated within a range of 50 1000 nm. The isotherm curves of the size controls and the roles of different experimental parameters are discussed. This feasible pathway may offer an ideal strategy of the size-controlled synthesis of hollow nanomaterials.