Abstract: We tested an affinity hemodialysis technique designed to efficiently remove HIV and toxic viral proteins from blood. Miniature polyethersulfone hollow-fiber dialysis cartridges (200–500 nm pore) were packed with anti-HIV antibodies covalently coupled to agarose beads and sealed inside the cartridge. Cell culture fluids, plasma, or infected blood (7–15 ml) containing HIV-1 were circulated over the cartridge at 0.7–10 ml/min and the rate of removal of HIV measured by PCR and p24 ELISA. The technique removed up to 98% of HIV-1 particles from cell culture supernatants. Affinity hemodialysis also efficiently captured cultured HIV from human blood plasma (90%) and native HIV from infected blood (83% to 100%). Viral capture followed first-order kinetics (t1/2 = 2.8 h). Variations in antibody type, matrix linkage (protein G versus direct coupling), bead pore size, and temperature of operation (25–37°C) had only small effects. Although some binding was nonspecific, direct binding to the immobilized antibodies appeared to be the predominant mechanism.