Oxidative and hydrolytic degradation reactions were carried out on teicoplanin in order to characterize the aromatic portion of the molecule and relate it to the other members of the class of glycopeptide antibiotics. Seven aromatic rings, obtained as triphenyl ether, diphenyl ether, and diphenyl moieties after oxidation and hydrolysis of teicoplanin, were identified. They are present in teicoplanin as aromatic amino acids and constitute the peptidic part of the molecule. The diphenyl ether and diphenyl moieties, which were isolated both as esters after oxidation and as α-amino acids after acid hydrolysis clearly indicate the nature of the corresponding amino acids in teicoplanin. The triphenyl ether moiety, which was isolated only as ester, allows the hypothesis that the corresponding amino acids are the same as those of the other glycopeptide antibiotics.