The N-[(3-amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] derivatives of amino acids were prepared starting from N-protected (Ac, Form, Bz, and Boc) 3-amino-1-(carboxymethyl)-o-carboranes and alkyl esters of natural amino acids using the carbodiimide method of coupling and removing the ester groups. All the amides obtained were diastereoisomeric mixtures. Some diastereoisomers were separated and the assignment of the absolute configuration of aminocarborane fragments was performed by X-ray crystallography