This paper illustrates the procedure for obtaining measurements of the shear wave velocity V_S by seismic dilatometer (SDMT) in backfilled boreholes in non-penetrable soils. The possibility of such measurement descends from the fact that the path of the shear wave from the surface to the upper and lower receiver includes a short path in the backfill of very similar length for both receivers. The SDMT equipment/test procedure and the borehole backfilling technique are briefly described. The validation of the method by comparison of parallel profiles of V_S obtained in the “virgin” soil and in a backfilled borehole is presented. V_S profiles obtained by SDMT in backfilled boreholes at two test sites in central Italy, Sulmona (coarse gravel) and L'Aquila (calcareous breccia), are compared to V_S profiles obtained by the traditional Down-Hole technique and related to the stratigraphic profiles of the subsoil.