The aims of this book is to investigate the effect of autoclave on the acylic powder itself for improving of some properties, by comparing these cured samples with control samples, and to study the effect of different polymerization techniques (curing process by two cycles of water-bath and curing by autoclave) on some properties of acrylic resin denture base material. Conclusions:On the light of the preceeding results, treatment powder of (PMMA) by autoclave produce an effect on the treated powder by improving some properties of acrylic resin. Treatment of acrylic powder with autoclave change its thermal behavior. The autoclave processing technique is a good alternative to the conventional water - bath processing technique.