- Glue sniffing (airplane glue) (see also Dependence) 304.6
- Glycinemia (with methylmalonic acidemia) 270.7
- Glycinuria (renal) (with ketosis) 270.0
- Glycogen
- Glycogenosis (see also Disease, glycogen storage) 271.0
- Glycopenia 251.2
- Glycopeptide
- Glycoprolinuria 270.8
- Glycosuria 791.5
- Gnathostoma (spinigerum) (infection) (infestation) 128.1
- Gnathostomiasis 128.1
- Goiter (adolescent) (colloid) (diffuse) (dipping) (due to iodine deficiency) (endemic) (euthyroid) (heart) (hyperplastic) (internal) (intrathoracic) (juvenile) (mixed type) (nonendemic) (parenchymatous) (plunging) (sporadic) (subclavicular) (substernal) 240.9
- Goldberg (-Maxwell) (-Morris) syndrome (testicular feminization) 259.51
- Goldblatt's
- Goldenhar's syndrome (oculoauriculovertebral dysplasia) 756.0
- Goldflam-Erb disease or syndrome 358.00
- Goldscheider's disease (epidermolysis bullosa) 757.39
- Goldstein's disease (familial hemorrhagic telangiectasia) 448.0
- Golfer's elbow 726.32
- Goltz-Gorlin syndrome (dermal hypoplasia) 757.39
- Gonadoblastoma (M9073/1)
- Gonecystitis (see also Vesiculitis) 608.0