Two different silicon nitride powders, one produced by self-propagating high-temperature synthesis (SHS) and one commercial, have been equally processed to obtain dense materials. Y2O3 powders as a sintering aid and hot-pressing techniques were used to process the materials. The fracture toughness and strength of the materials prepared have been evaluated and the results comparatively discussed as a function of the microstructure, with special emphasis on the characteristics of the initial powders.