The high-temperature durability of 85 mm tip diameter silicon nitride ceramic radial turbine rotors was evaluated with a hot gas spin test rig. The rotors withstood up to a turbine tip speed of 700 m/s at TIT of 1300°C under partially loaded conditions and 570 m/s at TIT of 1300°C under fully loaded conditions, respectively.The material of the rotors was a post-HIPed silicon nitride. The basic fatigue properties of the material were measured at high temperatures. In the hot gas spin test, the temperature and stress distributions at the turbine blade were calculated with a finite element method. The results of the hot-gas spin test are discussed by means of a failure prediction analysis on the basis of the Weibull statistics.