Two new taxane epoxides were isolated from the bark of Taxus brevifolia and their structures were established as lfl,9~-dihydroxy-4fl,20-epoxy-2~,,5~,7fl,10fl,13~-pentaacetoxy-tax-ll-ene and lfl,7fl-dihydroxy-4/~,20 epoxy-2~,5~,9~,10~,13u-pentaacetoxy-tax-ll-ene. These two compounds were found to readily isomerize via acyl migration upon standing in CDCI 3 solution and represent the first example ofintramolecular transesterification in this large family of taxane metabolites.