The results of investigations into the reaction of parabanic acid with formaldehyde at different molar ratios of the reagents are presented. A fast and effective method of synthesis of NN'-bis(hydroxymethyl)parabanate was developed. The reaction of parabanic acid with an excess of formaldehyde was analyzed and the structure of the products proposed. Conditions at which the hydroxymethyl derivatives of parabanic acid undergo self-condensation as well as prospects of using them in subsequent oxyalkylation with oxiranes are specified.