Chan-Shu and Blair's findings that xylene produces a strongly reactive eluate from red blood cells have been confirmed and extended. Alloantibodies of 21 different blood group specificities and red blood cells sensitized in vivo, including ABO sensitization of babies' blood, were tested. The xylene method produced stronger reacting eluates than the modified ether method in 70 per cent of the tests. Ether, acid, and heat methods never produced significantly stronger eluates than did xylene. Ether eluates prepared from red blood cells sensitized with anti-S and anti-s were nonreactive, but the same cells yielded easily detectable anti-S and anti-s when xylene eluates were prepared. The xylene method is sensitive and simple. In addition, xylene is not subject to such stringent control of storage conditions by inspection agencies as is ether.