Objective: The aim of this study was to evaluate the effect of gastric acid on different resin-based composites with surface microhardness. surface roughness and scanning electron microscopy (SEM). Methods: Three different composite resin restorative materials (Clearfil Majesty ES-2{Kuraray. Tokyo. https://countryscenesaddleryandpetsuppliers.shop/product-category/western-assorted/