The reactions of urea, methylurea and dimethylureas with glyoxylic acid and its methyl ester to give α-substituted hydantoic acid derivatives (4, 5, 6, 7) and substituted allantoic acid derivatives (8) is discussed. The cyclization of the hydantoates and allantoates to 5- substituted hydantoins (11, 12) is also described.