Interpolymer complexes containing polyaniline in the form of emeraldine radical-cations matched with poly(styrenesulfonate) or DNA polyanions were prepared via interchange reaction between polyaniline previously protonated with dodecylbenzenesulfonic acid and poly(styrenesulfonate) or DNA complexed with dioctadecyldimethylammonium chloride which proceeds in chloroform solution at ambient temperature. The reaction mechanism and reaction products were established using elemental analysis, UV-vis, IR, and electron spin resonance spectroscopic measurements. DNA complexed with polyaniline retains its double-helical conformation. The synthesized complexes reveal a considerable conductivity.