The objective of this study was to determine the effect of simulated microwave disinfection on the tooth/acrylic resin impact strength. Acrylic molar teeth with a wax stick attached to the ridge lap were included in brass flasks. Specimens were made with Classico thermopolymerized acrylic resin, according to the groups: 1 and 5 - tooth with no treatment (control); 2 and 6 – tooth bur abrasion; 3 and 7 – tooth bur retention; and 4 and 8 – tooth monomer etch. Eighty specimens (n=10) were polymerized in bath cycle at 74^ºC for 9 hours and deflasked after flask cooling. Specimen from groups 2, 4, 6 and 8 was submitted to simulated microwave disinfection in a microwave oven at 650W for 3 minutes. Impact strength test was performed with an Otto Wolpert-Werke machine (Charpy system) with an impact load of 40 kpcm. Fracture load value was transformed into impact strength as a function of the bond area (kfg/cm²). Collected data were submitted to ANOVA and Tukey’s test (α=.05) and results indicate that the simulated microwave disinfection decreased the impact strength in all treatments.