- Zahorsky’s syndrome B08.5 (herpangina)
- Zellweger’s syndrome E71.510
- Zenker’s diverticulum K22.5 (esophagus)
- Ziehen-Oppenheim disease G24.1
- Zieve’s syndrome K70.0
- Zika NOS A92.5
- Zinc
- Zollinger-Ellison syndrome E16.4
- Zona – see Herpes, zoster
- Zoophobia F40.218
- Zoster (herpes) – see Herpes, zoster
- Zygomycosis B46.9
- Zymotic – see condition