Abstract: The present invention is directed toward a prefabricated shower curb system for easily providing a shower area with a water-retaining curb. The prefabricated shower curb system is formed mainly by a body that has a C-shape and includes a recess, and that is preferably manufactured from a rigid foam material such as expanded polystyrene. The body is mounted onto a wood, aluminum, or other support member arranged along a shower floor entrance area. The support member is secured to the shower walls or to an adjacent support member through brackets. A waterproof liner is used to cover and protect the support member. An adhesive material and the tapered interior design of the body recess allow the curb to be firmly secured in place on the supper member. The extraordinary strength, light-weight, low-cost, and easiness of size adjustment make the system novel in the industry.