A variety of affinity cross-flow filtration (ACFF) experiments were conducted to evaluate the technique as a means of effectively separating biomolecules. Agarose particles, which contained a specific affinity ligand for the targeted protein, were used as "affinity escorts" in the ACFF process. Both conventional agarose particles (40-150 .mu.m) and small agarose particles (Superose, 11-15 .mu.m) were used as the basis for affinity escorts. Batch ACFF washing experiments were conducted in both constant-volume and volume-reduction modes and compared with model predictions. The different affinity ligand-adsorbate systems studied include Cibacron Blue and human serum albumin, Cibacron Blue and lysozyme, protein A and immunoglobulin G, and concanavalin A and horseradish peroxidase.