Report-no: FM 98-13; Author: Vieri Mastropietro Title: Renormalization group for the XYZ model Abstract: We study in a rigorous way the XYZ spin model by Renormalization Group methods. Keywords: Renormalization Group, Correlations, XYZ chain Vieri Mastropietro Universita' di Roma Tor Vergata Via del Fontanile di Scarcaricola 00133 Roma Italia vieri@ipparco.roma1.infn.it