Two recent techniques using xylene and chloroform for antibody elution from red blood cells (RBC) were compared with the most widely used ether and heat elution by means of a quantitative 125I-antiglobulin test. Free serum alloantibodies and cell-bound alloantibodies from in vivo sensitization of delayed hemolytic transfusion reactions and of hemolytic disease of the newborn as well as autoantibodies in autoimmune hemolytic disease were studied. With alloantibodies, xylene proved more efficient than chloroform (p less than 0.025), while both methods were superior to heat or ether elution (p less than 0.005). Autoantibody elution was equally effective with xylene and chloroform (p less than 0.1) but again better than heat or ether elution (p less than 0.02). However, no single method produced the strongest eluate with all antibodies studied. We conclude that xylene and/or chloroform elution are valuable implementations in RBC serology, but, in selected instances, the classical elution methods will retain their importance.