Abstract: The invention relates to a ribbed plate for a composite slab, the profile of which consists of protruding ribs formed in an essentially planar plate, the upper flanges of the ribs being surface profiled in order to achieve better adhesion between the ribbed plate and the concrete of the composite slab. According to the invention, the surface profiling of the upper flange of each rib consists of spaced apart corrugations extending essentially across the upper flange. Additionally, in the junction of the web between the sides of the rib and the upper flange there is formed a protruding longitudinal corrugation extending at least partly along a length of the rib.