Chiral piperazines were used as efficient catalysts in the addition of unmodified aldehydes to nitroalkenes. The nature of the solvent, temperature, and catalyst load were found to influence the outcome of the reaction. The products were obtained in good yields up to 88%, high diastereoselectivities up to 97:3, and high enantiomeric excesses up to 85%. Plain piperazine and its monohydrochloride were used efficiently as organocatalysts in the synthesis of racemic gamma-formylnitroalkanes. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).