Although the high (40 to 50 per cent) glycerol method of freezing red blood cells has many advantages, no feasible procedure for deglycerolizing with only a clinical centrifuge has been available. Thus this method has been restricted to blood centers that distribute a sufficient number of frozen cells to warrant the installation of automated cell washing equipment. However, by sedimenting the glycerolized cells prior to freezing and discarding the excess glycerol solution, postthaw deglycerolizing can be simplified to consist of an initial double dilution with hypertonic NaCl and isotonic saline-glucose followed by two cycles of sedimentation and resuspension in isotonic saline-glucose. The method is applicable to units frozen either at -80 C or in liquid nitrogen vapor. Units frozen in this way can also be deglycerolized in commercial automated cell washers using suitably modified protocols.