- Hydatidosis - see Echinococcus
- Hyde's disease (prurigo nodularis) 698.3
- Hydradenitis 705.83
- Hydradenoma (M8400/0) - see Hidradenoma
- Hydralazine lupus or syndrome
- Hydramnios 657
- Hydrancephaly 742.3
- Hydranencephaly 742.3
- Hydrargyrism NEC 985.0
- Hydrarthrosis (see also Effusion, joint) 719.0
- Hydremia 285.9
- Hydrencephalocele (congenital) 742.0
- Hydrencephalomeningocele (congenital) 742.0
- Hydroa 694.0
- Hydroadenitis 705.83
- Hydrocalycosis (see also Hydronephrosis) 591
- Hydrocalyx (see also Hydronephrosis) 591
- Hydrocele (calcified) (chylous) (idiopathic) (infantile) (inguinal canal) (recurrent) (senile) (spermatic cord) (testis) (tunica vaginalis) 603.9
- Hydrocephalic fetus
- Hydrocephalus (acquired) (external) (internal) (malignant) (noncommunicating) (obstructive) (recurrent) 331.4
- Hydrocolpos (congenital) 623.8
- Hydrocystoma (M8404/0) - see Neoplasm, skin, benign
