| Marburg Virus Disease |
| Marburg-like Viruses |
| Marchantia |
| Marek Disease |
| Marek Disease Vaccines |
| Marek's Disease-like Viruses |
| Marfan Syndrome |
| Margarine |
| Marginal Adaptation (Dentistry) |
| Marijuana Abuse |
| Marijuana Smoking |
| Marine Toxins |
| Marital Status |
| Marital Therapy |
| Marketing |
| Marketing of Health Services |
| Markov Chains |
| Marmota |
| Marriage |
| Marrubium |
| Mars |
| Marsdenia |
| Marsileaceae |
| Marsupialia |
| Martial Arts |
| Martinique |
| Masks |
| Masochism |
| Mason-Pfizer monkey virus |
| Mass Behavior |
| Mass Chest X-Ray |
| Mass Fragmentography |
| Mass Immunization |
| Mass Media |
| Mass Screening |
| Massage |
| Masseter Muscle |
| Massive Hepatic Necrosis |
| Mast Cells |
| Mast-Cell Sarcoma |
| Mastadenovirus |
| Mastectomy, Extended Radical |
| Mastectomy, Modified Radical |
| Mastectomy, Radical |
| Mastectomy, Segmental |
| Mastectomy, Simple |
| Mastectomy, Subcutaneous |
| Mastication |
| Masticatory Muscles |
| Mastigophora |
| Mastigophora Infections |
| Mastitis |
| Mastitis, Bovine |
| Mastocytoma |
| Mastocytosis |
| Mastocytosis, Cutaneous |
| Mastocytosis, Systemic |
| Mastoiditis |
| Masturbation |
| Matched-Pair Analysis |
| Materia Medica |
| Materials Management, Hospital |
| Materials Testing |
| Maternal Age |
| Maternal Behavior |
| Maternal Deprivation |
| Maternal Exposure |
| Maternal Health Services |
| Maternal Mortality |
| Maternal Nutrition |
| Maternal Welfare |
| Maternal-Child Health Centers |
| Maternal-Child Nursing |
| Maternal-Fetal Exchange |
| Maternal-Fetal Relations |
| Mathematical Computing |
| Matricaria |
| Matrilysin |
| Matrix Attachment Region Binding Proteins |
| Matrix Attachment Regions |
| Matrix Bands |
| Matrix Metalloproteinases |
| Maturation-Promoting Factor |
| Mauritania |
| Mauritius |
| Maus Elberfeld virus |
| Maxillary Artery |
| Maxillary Fractures |
| Maxillary Neoplasms |
| Maxillary Nerve |