The invention relates to an intersomatic cage comprising a body (3) and a part (2) that is designed to dilate the intersomatic space between two vertebrae (8, 8′) by rotating the cage so that the cage (1) can be inserted into the space. The body (3) has a prism shape with a substantially planar upper surface (6) which can bear against the superior vertebral endplate (8) and a substantially planar lower surface (6′) which can bear against the inferior vertebral endplate (8′).