Protective antigen and lethal factor components were isolated directly from crude culture supernatant of Bacillus anthracis by sequential immunosorbent chromatography using immobilized monoclonal antibodies (MAB) against the respective toxins. The immunological activity of protective antigen, lethal factor and edema factor were purified by 1.2-, 6.3- and 2.3-fold, respectively, with recoveries of 63, 70 and 46%, respectively. All three components retained biological activity when combined to form lethal toxin or edema toxin, PA + LF and PA + EF, respectively, after the purification process, and were not contaminated with any of the other components. The order of immunosorbent columns during the purification process was found to be important. The best results were obtained when the protective antigen was removed initially from the crude culture supernatant.