The present invention relates to an indexable insert (10) for turning having polygonal, preferably triangular basic shape including an upper surface (11), a bottom surface (12) and these interconnecting edge surfaces (13, 14, 15), at least a part of the intersecting lines between the edge surfaces and the upper surface forming at least a main cutting edge (19), a secondary cutting edge (18) and a curved corner region therebetween which is asymmetric and divided into a plurality of circular segments. The novelty of the invention is that the size of the radius of a radial edge (20) next to the secondary cutting edge shall be at least 5 times larger than the corner edge (21) located on the opposite side of the bisector and which provides a transition to the main cutting edge (19).