Derivatives of oleandomycin, its 11-monoalkanoyl and 11,2'-dialkanoyl esters having at the 4''-position an amino group substituted with -C(=X)-X-R3 wherein X is O or S and R3 is alkyl, phenyl or benzyl groups, each of which may be substituted or unsubstituted, or a pyridylmethyl group, their preparation and use as antibacterial agents is described.