Lenampicillin is an antibiotic drug of the penicillin class. It is a prodrug of ampicillin; after oral administration of lenampicillin, ampicillin is rapidly formed.

Lenampicillin inhibits bacterial penicillin binding proteins (transpeptidase) and is effective against a wide range of bacterial infections.

Lenampicillin was developed in Japan and has been marketed there.