Abstract Sulfohexyl methacrylate and its polymer have been prepared. The anticoagulation activity of this polymer and copolymers with hydroxyethyl methacrylate and acrylamide was compared with that of polyhydroxyethyl methacrylate, polysulfoethyl methacrylate, and heparin. The activated‐carbon microcapsule coated with polysulfohexyl methacrylate showed itself a promising adsorbent.