Abstract: The present invention relates to ketolide compounds of Formula I. The compounds have good anti-microbial activities, reduced inhibition of cytochrome P4503A4 (CYP3A4), and acceptable safety of co-administration of other drugs. The present invention also relates to a pharmaceutical composition comprising compounds of Formula I and the method of treating anti-microbial infection by administering the compounds. Oral administration is a preferred route of administration.