- Metamorphopsia 368.14
- Metaplasia
- Metastasis, metastatic
- Metatarsalgia 726.70
- Metatarsus, metatarsal - see also condition
- Methadone use 304.00
- Methemoglobinemia 289.7
- Methemoglobinuria (see also Hemoglobinuria) 791.2
- Methicillin
- Methioninemia 270.4
- Metritis (catarrhal) (septic) (suppurative) (see also Endometritis) 615.9
- Metropathia hemorrhagica 626.8
- Metroperitonitis (see also Peritonitis, pelvic, female) 614.5
- Metrorrhagia 626.6
- Metrorrhexis - see Rupture, uterus
- Metrosalpingitis (see also Salpingo-oophoritis) 614.2
- Metrostaxis 626.6
- Metrovaginitis (see also Endometritis) 615.9
- Mexican fever - see Typhus, Mexican
- Meyenburg-Altherr-Uehlinger syndrome 733.99
- Meyer-Schwickerath and Weyers syndrome (dysplasia oculodentodigitalis) 759.89
- Meynert's amentia (nonalcoholic) 294.0