A review of affinity membrane publications from 1989 to 1999 is presented containing six major divisions: (a) modification of existing membranes for affinity adsorption applications; (b) membranes specifically prepared for affinity binding; (c) module designs for immuno- and other affinity sorption processes; (d) the kinetics of the affinity sorption process; (e) a selection of interesting applications that have appeared during the period and (f) a summary of reviews published during the period. Although there have been a large number of membrane preparation and process applications described in the literature during the period covered by the review, the commercialization of affinity membranes remains meager: One purpose f the review is to point out opportunities for more applied development of affinity membranes, including the design of appropriate modules to house them. From the available literature it should be possible to produce high efficiency separation devices based on the combination of sieving and adsorption characteristics of affinity membranes.