A highly enantioselective reduction of prochiral 2H-azirines has been achieved, mediated by chiral copper-hydride complexes. Both alkylated and arylated mono- and trisubstituted 2H-azirines are reduced to afford N–H aziridines in high yields (up to 96%) and enantioselectivities (up to 96% ee). Such aziridines are building blocks of wide synthetic utility, and to demonstrate this, we executed a gram-scale synthesis of the aziridine precursor (96% ee) of a neuro-peptide Y Y5 receptor antagonist. D