The objective of this work is the development of a process for the purification of lectins with affinity membranes. To this aim affinity membranes were prepared by chemical modification of a cellulose matrix. Different ligands were tested endowed with the different affinity towards the lectins used. As a model protein a lectin obtained by chromatographic techniques from Momordica charantia seeds was mainly used; Peanut agglutinin and Ricinus communis agglutinin were also considered. Among the various ligands tested N-acetyl-d-galactosamine gave the best separation performances, whilst arabinogalactan gave the highest binding capacity. The ligand immobilized on the membrane surface is quantified indirectly by measuring the amount of protein bound to the membrane. The kinetics of adsorption and desorption of the purification process has been studied in detail for the different supports. Modified membranes have been used in separation process of lectins with good results in terms of binding capacity towards the protein of interest.