The in vitro adhesion testing is a valuable measurement for the effectiveness assessment of denture adhesives. The objective of this study was to assess the adhesion forces of adhesives powder, paste and gels. The test was performed with the Pi 3 methods. One way ANOVA and Dunnett T3 were used at 95% confident interval. The result showed that the adhesion forces of resin acrylic palatal plate in normal situation (without adhesive) were 9.9ฑ0.6 N. The adhesion forces were increased after using denture adhesives. Immediately after insertion, the adhesion force of gels was greater than paste and powder significantly. For a longer period of wearing, the adhesion force of paste were increased, as opposed to those of gels that decreased continuously. After wearing for 2 hours, the adhesion force of paste was highest and significantly different from the others, while the adhesion forces of gels (carbopol, carboxymethyl cellulose and gum tragacanth) and one powder were similar to without adhesive. Within the limitation of this study, it was concluded that well-fitting resin acrylic palatal plates could adhere to tissue without using any adhesives. The adhesive gels could increase the adhesion forces up to 3-4 times immediately, but they decreased continuously and was similar to without adhesive within 2 hours. The adhesion forces of paste increased with time of wearing. The increased adhesion forces of adhesive powder were lower than the paste.