- Myopathy 359.9
- Myopericarditis (see also Pericarditis) 423.9
- Myopia (axial) (congenital) (increased curvature or refraction, nucleus of lens) 367.1
- Myosarcoma (M8895/3) - see Neoplasm, connective tissue, malignant
- Myosis (persistent) 379.42
- Myositis 729.1
- Myospasia impulsiva 307.23
- Myotonia (acquisita) (intermittens) 728.85
- Myotonic pupil 379.46
- Myriapodiasis 134.1
- Myringitis
- Mysophobia 300.29
- Mytilotoxism 988.0
- Myxadenitis labialis 528.5
- Myxedema (adult) (idiocy) (infantile) (juvenile) (thyroid gland) (see also Hypothyroidism) 244.9
- Myxochondrosarcoma (M9220/3) - see Neoplasm, cartilage, malignant
- Myxofibroma (M8811/0) - see also Neoplasm, connective tissue, benign
- Myxofibrosarcoma (M8811/3) - see Neoplasm, connective tissue, malignant
- Myxolipoma (M8852/0) (see also Lipoma, by site) 214.9
- Myxoliposarcoma (M8852/3) - see Neoplasm, connective tissue, malignant
- Myxoma (M8840/0) - see also Neoplasm, connective tissue, benign
- Myxosarcoma (M8840/3) - see Neoplasm, connective tissue, malignant