China 
Africa 
- Wogonin
- Wolbachia
- Wolf Hirschhorn Syndrome
- Wolf-Hirschhorn syndrome
- Wolff Chaikoff effect
- Wolff's law
- Wolff-Parkinson-White syndrome
- Wolffian duct
- Wolfram syndrome
- Wolinella
- Wolman disease
- Women's Health Initiative
- Women's health
- Womersley number
- Wonder
- Wong-Baker Faces Pain Rating Scale
- Woodchuck hepatitis virus
- Woodcock Johnson
- Woolly hair
- Word catheter
- Word salad
- Work accident
- Work of breathing
- Work-related musculoskeletal disorders
- Work-up
- Workaholism
- Worker Protection Standard
- Working Formulation
- Working level
- Working memory
- Working memory training
- Workplace aggression
- Workplace bullying
- Workplace health promotion
- Workplace health surveillance
- Workplace violence
- Workplace wellness
- World AIDS Day
- World Mental Health Day
- Wormian bones
- Worry
- Worst-case scenario
- Worth 4 dot test
- Wortmannin
- Wound assessment
- Wound bed preparation
- Wound closure
- Wound contraction
- Wound dehiscence
- Wound dressings
- Wound healing
- Wounds
- Wright's stain
- Wrinkles
- Wrist
- Wrist arthroscopy
- Wrist drop
- Wrist joint
- Wrist osteoarthritis
- Writer's cramp
- Writing therapy
- Wrongful birth
- Wrongful life
- Wuchereria bancrofti
- X chromosome
- X chromosome inactivation
- X inactivation
- X-gal
- X-linked adrenoleukodystrophy
- X-linked agammaglobulinemia
- X-linked dominant inheritance
- X-linked hypophosphatemia
- X-linked ichthyosis
- X-linked intellectual disability
- X-linked lymphoproliferative disease
- X-linked myotubular myopathy
- X-linked recessive inheritance
- X-linked severe combined immunodeficiency
- X-linked thrombocytopenia
- X-pro aminopeptidase
- X-ray absorption spectroscopy
- X-ray crystallography
- X-ray detector
- X-ray diffraction
- X-ray fluorescence
- X-ray fluorescence spectroscopy
- X-ray image intensifier
- X-ray microtomography
- X-ray photoelectron spectroscopy
- X-ray tube
- X-ray tubes
- X-rays
- XCR1
- XIAP
- XIST
- XLD agar
- XLR-11
- XRCC1
- XRCC4
- XX gonadal dysgenesis
- XX male
- XX male syndrome
- XXY
- XY gonadal dysgenesis
- XYY syndrome
- Xaliproden
- Xanax
- Xanomeline
- Xanthan
- Xanthan gum
- Xanthelasma
- Xanthene
- Xanthine
- Xanthine dehydrogenase
- Xanthine oxidase
- Xanthine oxidase inhibitor
- Xanthium
- Xanthium strumarium
- Xanthochromia
- Xanthogranuloma
- Xanthogranulomatous
- Xanthoma
- Xanthoma disseminatum
- Xanthomonas
- Xanthomonas campestris
- Xanthomonas oryzae
- Xanthone
- Xanthonoid
- Xanthophyll
- Xanthopsia
- Xanthosine
- Xanthosoma
- Xanthotoxol
- Xanthurenic acid
- XbaI
- Xenobiotic metabolism
- Xenobiotics
- Xenodiagnosis
- Xenoestrogens
- Xenografts
- Xenon
- Xenophagy
- Xenopus
- Xenorhabdus
- Xenotransplantation
- Xerophthalmia
- Xerosis
- Xerostomia
- Ximelagatran
- Xipamide