The present invention relates to a vertebral implant, in particular for corpectomy, to a device for attaching a vertebral implant and to implantation instrumentation, the implant including at least one first body (2) and at least one second body (3) each having at least one face having shapes and dimensions mating those of at least one face of another body (3, 2) and forming mutual fitting means, in order to allow assembling of said bodies (2, 3) by sliding along a sliding axis and, on the other hand, at least one locking means (4) retained in at least one of the bodies (2, 3) and at least one abutment portion of which is laid out for passing from a so-called open position, allowing sliding for the assembling of said bodies (2, 3), to a so-called closed position, locking said bodies (2, 3) assembled together by the contact between at least said abutment portion and at least one abutment (42, 43) of at least one of said bodies (2, 3), said abutment (42, 43) being oriented not parallel to the sliding axis and said abutment portion passing from the open position to the closed position elastically by flexure or torsion.