Abstract: The modular support for staircase steps comprises a substantially vertical box-like body upwardly defining a horizontal base plane for a related step, a male cylindrical element and a complementarily shaped female cylindrical element extending vertically at two different levels at the opposite longitudinal ends of said box-like body and adapted to be coupled in an angularly adjustable position to corresponding cylindrical elements of adjacent supports, said male cylindrical element being less extended vertically with respect to said female cylindrical element so as to allow an adjustment of the mutual axial position by means of the insertion of suitable spacer means, substantially axial means along finally provided for the locking of said coupled cylindrical elements.