Reduction of N-substituted azetidin-2-ones to N-substituted azetidines was accomplished rapidlyand in good yield with diborane in tetrahydrofuran and with alane in ether. The stereochemistryof the ring substituents was retained under the reaction conditions. 3-Aminopropanol derivativesformed by reductive ring cleavage were sometimes obtained as by-products in diborane reductionsbut not in alane reductions. The reductions of fourteen azetidin-2-ones to azetidines with diboraneand eighteen with alane are reported.