The exciton coupled CD method has been applied to determine the absolute configuration of the diepoxins, spiroketal-linked naphthodiepoxydecalinones of fungal origin. The CD spectra of the bis-dimethylaminobenzoate derivatives of the diepoxins ?, ? and ?, reveal a positive chiral twist between the two substituted hydroxyl groups and thus infer theS configuration at both of these stereogenic centers. The absolute configuration of the remaining chiral centers is deduced from their relative configurations as established by X-ray diffraction of diepoxin ?. The twist boat conformation of the epoxycyclohexanone ring and the continued axial orientation of the substituents at C-4 and C-5 after dimethylaminobenzoate derivatization was corroborated by1H-NMR coupling constants.