In a cutting insert and a milling tool, where the cutting insert is to be on-edge mounted to the tool, the cutting insert includes a polygonal body of wear resistant material. The body includes a first side surface and a second side surface opposing one another and therebetween a number of end surfaces. The intersection of two end surfaces form a cutting edge at a corner portion. The first side surface is substantially planar and the second side surface connects to raised portions at corner portions. The first side surface is greater than the second side surface.