- Nose, nasal - see condition
- Nosebleed 784.7
- Nosomania 298.9
- Nosophobia 300.29
- Nostalgia 309.89
- Notch of iris 743.46
- Notched lip, congenital (see also Cleft, lip) 749.10
- Notching nose, congenital (tip) 748.1
- Nothnagel's
- Novy's relapsing fever (American) 087.1
- Noxious
- Nuchal hitch (arm) 652.8
- Nucleus pulposus - see condition
- Numbness 782.0
- Nuns' knee 727.2
- Nursemaid's
- Nutmeg liver 573.8
- Nutrition, deficient or insufficient (particular kind of food) 269.9
- Nyctalopia (see also Blindness, night) 368.60
- Nycturia 788.43
- Nymphomania 302.89
- Nystagmus 379.50