The reduction by sodium and ethanol, with or without liquid ammonia as solvent, of various amidines followed by acid hydrolysis, leads in many cases to a good yield of the corresponding aldehyde. Further reduction in liquid ammonia of several 2-aryl-imidazolines or imidazolidines followed by acid hydrolysis leads to the 2,5-dihydro-benzaldehyde derivative. The reduction of some acid amides by sodium and proton sources in liquid ammonia has been examined. Under the right conditions this process is of preparative value for aldehydes.