The fracture energy of superplastically forged silicon nitride, where rodlike silicon nitride grains are aligned in one direction, was investigated at high temperatures from 1100 degrees to 1300 degreesC and at room temperature. Bending tests using chevron-notched beams were conducted at two displacement rates, 0.05 and 0.005 mm/min. The superplastically forged silicon nitride showed remarkably high fracture energies, 200-630 J/m(2). The fracture energy was largely dependent on the temperature and the displacement rate. The high fracture energy was attributed to grain pullout enhanced by the softened grain-boundary glassy phase and the aligned rodlike grains.