Uniform agarose-polymeric microsphere beads of 1 mm diameter were synthesized by encapsulating appropriate polymeric microspheres in an agarose matrix. The potential use of these beads for hemoperfusion was demonstrated. Agarose provides the high porosity and the biocompatibility of the beads; the encapsulated microspheres are used for the removal of harmful substances from the circulatory system. Two types of polymeric microspheres were prepared: (a) polymercaptal microspheres of 0.8 micrometer average diameter; (b) polyacrolein microspheres of 0.2 micrometer average diameter. Agarose-polymercaptal microsphere beads were designed for the removal of heavy metals by hemoperfusion. As a model, the detoxification of mercury compounds was studied. Agarose-polyacrolein microsphere beads were designed for the removal of antibodies by hemoperfusion, especially in autoimmune diseases. As a model, the removal of anti-BSA from immunized animals was studied.