sufficient absorptiona quantitative method to replace exhaustive absorption at present the only guideline for removal of undesired reactivities from an antiserum is that no activity against the crossreacting undesired antigens should remain after exhaustive absorption since this guideline sets no upper limit on the amount of undesired antigens required for an exhaustive absorption waste of possibly precious material and of time in performing multiple sequential absorptions can result to minimize the quantity of antigen and of experimental work required for an absorption a quantitative approach is suggested the antiserum is testabsorbed with various amounts of the undesired antigens and antibody activity still present against these antigens is then tested the results can be plotted as a curve by use of reifs modification of the von krogh equation thus the exact amount of undersired antigens sufficient to remove all detectable reactivity against these antigens can be determined the procedure is termed sufficient rather than exhaustive absorption to stress that only detectable amounts rather than every last trace of undesirable antibodies have been removed the nomenclat re exhaustive absorption gives no indication that any practical attempt to achieve it can hardly escape having the same limitations as sufficient absorption it is therefore suggested that the misleading nonquantitative nomenclature exhaustive absorption be eliminated from immunological terminology sufficient absorption has been applied to the absorption of undesired blood group antibodies from rabbit antisera to cea