The purpose of this study was to investigate bond strength of denture base resin repairedaccording to contamination. One commercial denture base resin and two different kinds of relinesresin were tested; Lusiton 199(denture base resin), Vertex(reline resin) and TokusoRebase(repairresin). The specimens were processed according to the manufacturer's instructions to cured denturebase resin(polymethylmethacrylate; PMMA) and reline resin. Bond strengths were examined byuse of a three-point transverse flexural strength test. Data were analyzed with two-factor analysis ofvariance and Duncan's post-hoc test at =0.05. Generally, the bondstrength of heat-curedresin(Lusiton 199) was higher than the other resins. The contaminations produced an decrease inbond strength. Therefore the contamination, such as saliva or water must be avoided during thelaboratory repair procedures.