Abstract: The present invention relates to an improved glenoid anchor for a shoulder joint prosthesis, in particular a convertible prosthesis, of the type intended to be fixed to the glenoid cavity of the shoulder blade and comprising:—a pin (2) with an internally hollow and essentially thimble-like conical sleeve (12), which has a tapered distal end (3) and an open proximal end (4);—an annular recess (15) formed inside the cavity (13) of the pin (2) in the vicinity of said open proximal end (4), for receiving by means of snap-engagement an edge (34) of a lug (30) of a prosthesis component (9);—at least one pair of oppositely arranged anti-rotation notches (16, 17) in the proximity of said annular groove (15) for receiving by means of snap fit oppositely arranged teeth (18, 19) of the same lug (30) intended to be snap-engaged together with said pin (2).