An extraction chromatographic technique has been developed for the separation of carrier-free Y-90 from the Sr-90 present in the high level waste (HLW) of the Purex process. When a Purex HLW solution in 2-3 M HNO3 is passed through a CMPO-Chromosorb-102 (CAC) column, all the trivalent, tetravalent, and hexavalent ions are sorbed. The effluent from this experiment, after adjusting the pH to 2 with NaOH, was passed through a 2-ethylhexyl-2-ethylhexyl phosphonic acid (KSM-17)-Chromosorb-102 (KSMC) extraction chromatographic column where only Y-90 was sorbed. All the other ions (Sr-90, Cs-137, Sb-125, Ru-106, Rh-106, etc.) were washed off with dilute HNO3 (pH 2), and carrier-free Y-90 was eluted with 0.5 M HNO3. This technique can yield Y-90 in mCi levels in pure form for medical applications. The Sr-90 can be used repeatedly after allowing for Y-90 buildup.