The present invention relates to an interspinous implant (1), intended to be implanted between two adjacent dorsal spines (EI, ES), each including an upper edge (E2), a lower edge (E3) and two opposed lateral faces (E4, E5), wherein the implant (1) includes at least one body (10) with dimensions arranged so as to maintain or restore a distance between the adjacent edges (E2, E3) of the two spinous processes (EI, ES) and including at least two wings (11, 12) extending so that at least a part of each wing (11, 12) lies along at least a part of one lateral face (E4, E5) of one of the two spinous processes (EI, ES) and, additionally, at least one retainer (2, 3, 4, 7, 111, 121, 221, 24, 28, 29, L, 90) for the implant, designed to retain the body (10) of the implant between the two spinous processes and to be inserted from the same lateral face as the body (10).