Relative stabilities of alpha-, beta- and gamma-ketonic and enolic radicals have been examined using U/P/ROMP2 and UDFT methods. Our results show that in alpha- and gamma-radicals, UMP2 and DFT schemes all favor ketonic form. However, in beta-radicals, the UMP2 favors ketonic radical in keto-enol tautomerization of compound containing a radical at beta position whereas DFT and CCSD(T) schemes prefer enolic ones. The failure of beta-radicals for UMP2 method comes from the large effect of spin contamination for enolic form, and can be corrected by using ROMP2 and PMP2 methods. (C) 2013 Elsevier B.V. All rights reserved.