So far very little work has been reported on the preparation and properties of 4imidazolidinones 1. The known methods involve reduction of either thiohydantoins 2 (2) or 4'(5)-imidazolones 3 (3). In this paper we wish to report a rather convenient synthesis of 3- hydroxy-4imidazolidinones (6a-61), which is based on the reaction of aliphatic a- aminohydroxamic acids with aromatic aldehydes.