- Leukoma (cornea) (interfering with central vision) 371.03
- Leukomalacia, periventricular 779.7
- Leukomelanopathy, hereditary 288.2
- Leukonychia (punctata) (striata) 703.8
- Leukopathia
- Leukopenia 288.50
- Leukopenic - see condition
- Leukoplakia 702.8
- Leukopolioencephalopathy 330.0
- Leukorrhea (vagina) 623.5
- Leukosarcoma (M9850/3) 207.8
- Leukosis (M9800/3) - see Leukemia
- Lev's disease or syndrome (acquired complete heart block) 426.0
- Levi's syndrome (pituitary dwarfism) 253.3
- Levocardia (isolated) 746.87
- Levulosuria 271.2
- Lewandowski's disease (primary) (see also Tuberculosis) 017.0
- Lewandowski-Lutz disease (epidermodysplasia verruciformis) 078.19
- Lewy body dementia 331.82
- Lewy body disease 331.82
- Leyden's disease (periodic vomiting) 536.2
- Leyden-Möbius dystrophy 359.1