A refining surface for a refiner intended for defibrating lignocellulose-containing material, the refiner comprising at least two refining surfaces arranged coaxially relative to each other, at least one of which rotates around a shaft, and between which the material to be defibrated is fed. The refining surfaces comprise grooves and between them ridges, at least part of the refining surface ridges being formed of at least two different ridge parts connected to each other in such a way that one ridge part is farther ahead in the rotation direction of the refining surface than the other ridge part. Further, at least in some ridge parts, the front wall in the rotation direction of the refining surface is over at least part of its length substantially inclined.