An exchangeable cutting insert comprises a front cutting portion having an operative front surface with two lower corners and at least one upper corner, and a trailing mounting portion extending rearwardly therefrom. The front cutting portion is formed with a major cutting edge extending between the two lower corners and a minor side edge extending between one of the lower corners and said upper corner. The minor side edge is substantially perpendicular to the major cutting edge. The major cutting edge has two trailing extremities associated with the lower corners, and having a leading extremity which protrudes outwardly and is raised upwardly relative to the trailing extremities.