Diethylcarbamazine (DEC) reacted with liver cell plasma membrane of rodent hosts-cotton rat, albino rat and Mastomys natalensis exhibiting the presence of both saturable and unsaturable components. The presence of lectins or sugar derivatives did not affect the binding significantly. The drug showed similar binding pattern with serum but the saturation was reached at a much lower concentration of the ligand. Data obtained with a variety of macromolecules, particularly with the homopolymers of amino acids indicate that DEC does not require any specific constituent of the membrane for binding. The nonspecific nature of DEC binding does not provide any convincing clue for the accumulation of microfilariae specifically in the liver following the drug treatment.