Abstract Novel 4 ″-O-benzimidazolyl clarithromycin derivatives were designed, synthesized and evaluated for their in vitro antibacterial activities. These benzimidazolyl derivatives exhibited excellent activity against erythromycin-susceptible strains better than the references, and some of them showed greatly improved activity against erythromycin- resistant strains. Compounds 16 and 17, which have the terminal 2-(4-methylphenyl) ...