Transparent hydroxyapatite (HAp) sintered body with a high crystal orientation and a relative density of 99.7% was fabricated by the pulse electric current sintering method; the c-axis of HAp crystals with a hexagonal column morphology and ca. 200 pm x 25 pm in size was oriented perpendicular to the pressure direction. The sintered temperature increased to 1200degreesC at a heating rate of 50degreesC/min for 10 min and a pressure of 50 MPa was applied. The orientation indexes were calculated from X-ray diffraction patterns of the planes perpendicular and parallel to the pressure direction. The optical transmittance was greater than 70% over the wavelength of 700 nm.