- Maan Pharma
- Macheal Lab
- Madras Pharmaceuticals
- Magbro Healthcare
- Makcur Laboratories
- Makin Laboratories
- Maple
- Marcburg
- Marine Lifesciences
- Matsutatni Chemical
- Maxtar Bio-genics
- Mc Graw Pharma
- Mead Johnson Nutrition
- MEDA Pharma
- Medchem Int'l
- MedChoice Endocrine Group
- MedChoice Pharma
- MedChoice Women's Health
- MedEthix
- Medhaus
- Medica Korea
- Medica Pedia
- Medicamen Organics
- Medicamenta
- Medichem
- Medico Remedies
- Medinova
- Medi-Rx
- Medisure
- Mediwin
- Medley Pharma
- Medlink Pharma
- Medreich
- Medspecialty
- Meedpharma
- Mefar Ilac
- Mega Lifesciences
- Meiji Seika
- Mepro Pharmaceutical
- Merck
- Merck Sharp & Dohme
- Mercury Drug
- Mergers Drugfil
- Mergfil
- Merit Organics
- Merz
- Metro Drug
- Metro Pharma
- Metropolitan Pharma
- Metropolitan Pharmaceutical Products, Inc.
- Meyer Organics
- Meyers
- MG Co
- Micro Labs
- Milan Laboratories
- Millimed
- Mirabell
- Miraculin Pharma
- Moleac
- Mount Mettur
- MPSI
- MSD International GmBH (Puerto Rico)
- MSD International GmbH (SG)
- MSN Lab
- Multicare
- Mylan Labs
- Myungmoon