A fully relativistic scheme is presented that allows one to describe the magnetic Extended X-ray Absorption Fine Structure (MEX-AFS) in disordered systems. This method is based on a combination of the relativistic multiple scattering theory and the Coherent Potential Approximation (CPA) alloy theory. The alloy systems Fe=Coz-= and FexPtl-= are used to illustrate the ability of this theoretical approach due to the availability of suitable experimental data. For the latter system a rather pronounced impact of the degree of order on the MEXAFS has been found.