Novel series of novel 4''-O-arylalkylcarbamoyl and 4''-O-((arylalkylamino)-4-oxo-butyl)carbamoyl clarithromycin derivatives were designed, synthesized and evaluated for their in vitro antibacterial activities. These derivatives retained excellent activity against the erythromycin-susceptible strains and showed significantly improved activity against all of the tested erythromycin-resistant strains. Among them, compound 4c was the most effective (0.06 microg/mL) against Streptococcus pneumonia encoded by the erm gene and compound 4a was had the most potent activity (0.25 microg/mL) against S. pneumonia encoded by the erm and mef genes.