- Naegeli's
- Naffziger's syndrome 353.0
- Naga sore (see also Ulcer, skin) 707.9
- Nägele's pelvis 738.6
- Nager-de Reynier syndrome (dysostosis mandibularis) 756.0
- Nail - see also condition
- Nanism, nanosomia (see also Dwarfism) 259.4
- Nanukayami 100.89
- Napkin rash 691.0
- Narcissism 301.81
- Narcolepsy 347.00
- Narcosis
- Narcotism (chronic) (see also Dependence) 304.9
- NARP (ataxia and retinitis pigmentosa syndrome) 277.87
- Narrow
- Narrowing
- Narrowness, abnormal, eyelid 743.62
- Nasal - see condition
- Nasolacrimal - see condition
- Nasopharyngeal - see also condition
- Nasopharyngitis (acute) (infective) (subacute) 460
- Nasopharynx, nasopharyngeal - see condition