Rifampicin (INN) or rifampin (USAN) is an antibiotic drug of the rifamycin group. It is typically used to treat mycobacterium infections, including tuberculosis and leprosy; and also has a role in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) in combination with fusidic acid. It is currently marketed by Aventis under the trade names Rifadin® and Rimactane®.

Rifampicin inhibits DNA-dependent RNA polymerase in bacterial cells by binding its beta subunit, thus preventing transcription of messenger RNA (mRNA) and subsequent translation to proteins.