The steady‐state creep behavior of reaction‐bonded silicon nitride, prepared by slip casting and injection molding, was examined in 4point bending with stresses ranging from 10,000 to 20,000 psi at temperatures from 1200° to 1450°C. Creep rates were proportional to the 1.4 power of the stress. The creep process exhibited an activation energy of 130±5 kcal/mol. The microstructure of deformed specimens, which was revealed by transmission and scanning electron microscopy, contained triple‐point voids suggesting that the rate‐controlling mechanism of creep is grain‐boundary sliding.