[reaction: see text]. Upon treatment with lithiumorganic nucleophiles, trans-configured oxiranyl carbaldimines are transformed into anti-configured cis-aziridinyl alcohols with excellent diastereoselectivity. This conversion may be explained by a new type of the aza-Payne rearrangement, including first a nucleophilic attack on the imine carbon atom with diastereofacial differentiation followed by an intramolecular nucleophilic opening of the oxiranyl ring with simultaneous formation of the aziridine ring.