- Waldenstrom's Macroglobulinemia see Lymphoma
- Walkers see Mobility Aids
- Walking Pneumonia see Pneumonia
- Walking Problems
- Walleye see Eye Movement Disorders
- Warts
- Water see Drinking Water
- Water Pollution
- Water Safety (Recreational)
- Waterborne Diseases see Water Pollution
- Weariness see Fatigue
- Wegener's Granulomatosis see Granulomatosis with Polyangiitis
- Weight Control
- Weight Loss Surgery
- Weight Training see Exercise and Physical Fitness; Sports Fitness
- Weight-Loss Diet see Diets
- West Nile Virus
- Wheat Allergy see Food Allergy
- Wheelchairs see Mobility Aids
- Whiplash see Neck Injuries and Disorders
- Whooping Cough
- Wildfires
- Wilms Tumor
- Wilson Disease
- Windpipe Disorders see Tracheal Disorders
- Winter Weather Emergencies
- WNV see West Nile Virus
- Women's Health
- Women's Health Checkup
- Wounds and Injuries
- Wrinkles see Skin Aging
- Wrist Injuries and Disorders