The dimensional stability, in particular polymerization shrinkage, of pattern resins affects the accuracy of implant prosthesis fabrication. Recently introduced photopolymerizing pattern resins are easy to use, but their shrinkage needs to be determined and compared with traditional autopolymerizing pattern resins.The purpose of the study was to compare the polymerization shrinkage of photopolymerizing pattern resins with autopolymerizing pattern resins.Two autopolymerizing (DuraLay, GC Pattern resin) and 2 photopolymerizing (Primopattern LC Gel, Primopattern LC Paste) pattern resins were tested. The sample size was 10 for each group. Polymerization shrinkage was determined by measuring the change in area dimensions with image analysis. The percentage of volumetric shrinkage was calculated, and the results were statistically analyzed with ANOVA, followed by the Student-Newman-Keuls post hoc test (α=.05).The volumetric shrinkage values (%; mean ±standard deviation) for GC Pattern Resin were 5.72 ±0.89; for DuraLay, 5.07 ±1.36; for Primopattern LC Gel, 5.42 ±1.83; and for Primopattern LC Paste, 7.43 ±0.62. The volumetric shrinkage of the Primopattern LC Paste was significantly higher than that of the other 3 materials.The photopolymerizing pattern resin in gel form (Primopattern LC Gel) had a similar shrinkage value to the autopolymerizing pattern resins (DuraLay and GC Pattern Resin). However, the photopolymerizing pattern resin in paste form (Primopattern LC Paste) shrank significantly more than the other 3 materials tested.