1. A new method of synthesis of substituted α,α-diaminocarboxylic acids was suggested and developed; it starts with α-amino acids and passes through the corresponding oxazolinones and 4-bromooxazolinones; amides 2. A method of synthesis of substituted α,α-diaminocarboxylic acids was suggested; this consists of heating α-hydroxy-α-acylamino acids with acid amides; this method permits one to prepare various α,α-bis-(acylamino) acids.