The apparent transition temperature (T-c) and enthalpy (DeltaH) of monoclinic (P2(1)/b) <----> hexagonal (P6(3)/m) reversible phase transition in stoichiometric (Ca/P = 5/3) hydroxyapatite were investigated as a function of hearing/cooling rate by means of a differential scanning calorimeter (DSC), in the heating/cooling rate range of 0.5-3.0 K/min. The apparent T-c value slightly increased and decreased with increasing heating and cooling rates, respectively, while the apparent DeltaH value was almost same within the experimental error.