Patients commonly have restorations in posterior teeth, made of resin-based composite, amalgam or glass ionomer or another material. Questions remain concerning the need for replacement of posterior restorations after bleaching. It's not clear if the bleaching agents exert some effect on the restorative materials that could harm the quality and longevity of these restorations. The aim of this study is to evaluate the effect of in home bleaching material on the compressive strength of different direct restorative materials. Three types of direct restorative materials: (two types of light activated composites, TG fine glass (Technical & General Ltd, Germany); Cavex (Quadrant Universal LC, CE 0197; Germany)) and one type of amalgam restorative material; World-Cap (Ivoclar vivadent FL-9494 schaan/Liechtenstein, Sweden) were used in this study. Forty resin composite specimens and 20 amalgam specimens were prepared using a circular nickel-chromium split mold with 3 mm in inner diameter and 6 mm in height. The twenty samples of each restorative material being selected were divided into 2 groups: ten tested before treatment with home bleaching tooth whitening system and the other ten, tested after treatment with home bleaching system (WHITE smile HOME BLEACHING, 35% carbamide peroxide, Germany) for 8 hours: (4X2 hours). Specimens were placed into a dark bottle containing distilled water at 37°C for 7 days before testing procedure. Compressive testing was performed in a Universal Testing Machine at a crosshead speed of 0.5 mm/min. The data was calculated in MPa and data were analyzed by one way ANOVA at 0.05 level of significance. All direct restorative materials being tested, exhibited statistically insignificant differences (P≥0.05) in compressive strength values between the two groups (before and after bleaching) except for TG direct restorative composite, which exhibited statistically significant differences (P<0.05) in compressive strength values between the two groups (before and after bleaching). All the restorative materials being tested exhibited lower compressive strength values after bleaching in comparison with their values before bleaching. In-Home bleaching material should not be used when TG light activated composite restorations.