- Monoamine Oxidase Inhibitors
- Mood Disorders
- Motion Sickness
- Movement Disorders
- Movement Therapy
- Mucopolysaccharidoses
- Mucormycosis
- Multiple Chemical Sensitivity
- Multiple Endocrine Neoplasia Syndromes
- Multiple Myeloma
- Multiple Personality Disorder
- Multiple Pregnancy
- Multiple Sclerosis
- Multiple-Gated Acquisition (MUGA) Scan
- Mumps
- Munchausen Syndrome
- Muscle Relaxants
- Muscle Spasms and Cramps
- Muscular Dystrophy
- Mushroom Poisoning
- Music Therapy
- Mutism
- Myasthenia Gravis
- Mycetoma
- Mycobacterial Infections, Atypical
- Mycoplasma Infections
- Myelodysplastic Syndrome
- Myelofibrosis
- Myelography
- Myers-Briggs Type Indicator
