A simple and efficient method has been developed which describes KOH-oriented catalytic regioselective ring-opening reactions of various N-tosylaziridines with malonates. In the presence of 20 mol% KOH, most N-tosylaziridines can smoothly react with malonates to give the corresponding products in good to excellent yields (up to 99%) and with good to excellent regioselectivity under mild experimental conditions. (c) 2012 Elsevier B.V. All rights reserved.