The separation of albumin from salts and buffers by AG 11A8 ion-retardation resin was studied as a function of column length, ion load, flow rate, and resin regeneration. These operating conditions affected the retardation of the low molecular weight ions and, thus, improved the separation from albumin which was cluted rapidly. Experimental conditions are described for separating albumin from NaCl, Tris-HCl, sodium trichloroacetate, sodium 5-sulfosalicylate, sodium citrate, sodium acetate, sodium phosphate, and ammonium sulfats. A 200-cm column is necessary for the effective separation of the last four compounds from albumin. The resin was used to separate bradykinin and related peptides from salts and buffers present in ethanol extracts of trypsin-treated plasma, as reported in the accompanying paper (Reis, M. L., Draghetta, W., Camargo, A. C. M., and Greene, L. J. (1977) Anal. Biochem. 81, 358–368.