China 
Africa 
- Xiphoid process
- Xiyanping
- Xq28
- Xylan
- Xylanase
- Xylazine
- Xylem
- Xylene
- Xylitol
- Xyloglucan
- Xylometazoline
- Xylooligosaccharide
- Xylose isomerase
- Xylosyltransferase
- Y RNA
- Y STR
- Y chromosome
- Y chromosome microdeletion
- Y-27632
- Y-set
- YAP1
- YBX1
- YRBSS
- YY1
- Ya ba
- Yak butter
- Yale Food Addiction Scale
- Yale Global Tic Severity Scale
- Yale-Brown Obsessive Compulsive Scale
- Yam
- Yamogenin
- Yams
- Yang deficiency
- Yangonin
- Yangsheng
- Yates's correction for continuity
- Yawn
- Yaws
- Years of potential life lost
- Yeast
- Yeast artificial chromosome
- Yeast cells
- Yeast extract
- Yellow Card Scheme
- Yellow fever
- Yellow fever vaccine
- Yellow fever virus
- Yellow nail syndrome
- Yeoman's test
- Yerba mate
- Yergason's test
- Yerkes-Dodson law
- Yersinia
- Yersinia enterocolitica
- Yersinia pestis
- Yersinia pseudotuberculosis
- Yersinia ruckeri
- Yersiniosis
- Yew
- Yin deficiency
- Yoda1
- Yoga
- Yoga nidra
- Yohimbine
- Yolk sac
- Young Mania Rating Scale
- Young adults
- Young carers
- Young's operation
- Young's syndrome
- Young-Burgess classification
- Yttrium 90
- Yttrium aluminum garnet
- Yttrium lithium fluoride
- Yttrium oxide
- Yuanqi
- Yuzpe regimen
- Z drugs
- Z score
- Z-DNA
- Z-factor
- Z-plasty
- Z-value
- ZAP70
- ZAP70 deficiency
- ZD6126
- ZEB1
- ZEB2
- ZFY
- ZM447439
- ZMapp
- ZNF217
- ZNF3
- ZP1
- Zafirlukast
- Zaire ebolavirus
- Zalcitabine
- Zaleplon
- Zalutumumab
- Zanamivir
- Zangfu
- Zanthoxylum piperitum
- Zanthoxylum rhetsa
- Zap-70 deficiency
- Zap70
- Zaprinast
- Zea mays
- Zearalenone
- Zeaxanthin
- Zebularine
- Zein
- Zeitgebers
- Zejula
- Zelen's design
- Zellballen
- Zellweger syndrome
- Zenker's diverticulum
- Zeolites
- Zepatier
- Zeranol
- Zibotentan
- Ziconotide
- Zidovudine
- Ziehl-Neelsen stain
- Zieve syndrome
- Zieve's syndrome
- Zika
- Zika Forest
- Zika fever
- Zika virus
- Zileuton
- Zimelidine
- Zimmermann-Laband syndrome
- Zinc acetate
- Zinc chloride
- Zinc citrate
- Zinc deficiency
- Zinc finger protein
- Zinc finger transcription factors
- Zinc fingers
- Zinc gluconate
- Zinc oxide eugenol
- Zinc phosphate
- Zinc phosphide
- Zinc picolinate
- Zinc protoporphyrin
- Zinc pyrithione
- Zinc toxicity
- Zinc transporter protein
- Zingerone