Poor adaptations of acrylic resin denture bases to the supporting tissues markedly decrease denture retention. Several denture base resin and processing techniques have been introduced to the profession, each claiming to produce a more accurate base. Microwave processing techniques has been introduced claims to minimize the dimensional changes.This purpose of this study was to compare the dimensional accuracy of three denture base resins when processed both by conventional water bath method and by use of microwave energy. Three Poly (MethylMethacrylate) heat cure resins selected for this study. These resins were processed by conventional water bath technique for 1 1/2 hours at 75 degree & half hour at 100 degree and by microwave energy for 3 mins at 500W. The measurements of acrylic resin denture base specimens were compared with the measurements of master metal die dimension keeping it as a standard measurement. The mean values of the difference in the points compared were calculated, & compared to each other to determine if there was a statistically significant difference between them at the 0.05 probability level using the students' independent test for pooled variances