α-Alkyl-α-aryl (trimethyltin) nitriles react spontaneously with aldehydes and ketones in THF/toluene to give β-hydroxy nitriles with satisfactory to good yields and diastereoselectivity. No extra catalyst is required in this aldol-likereaction. A possible trimethyltin-substituted ketene imine intermediate is invoked as reactive species. DFT calculations offer good support for this hypothesis.