eBizMBA provides rankings of webiste volume by various content categories, including healthcare. The3 eBizMBA Rank is "a continually updated average of each website's Alexa Global Traffic Rank, and U.S. Traffic Rank from both Compete and Quantcast."

Here are their top 15 healthcare websites as of October 1, 2016, with corresponding estimated inuqie monthly visitors:

1. Web MD   - 80,000,000 Unique Monthly Visitors 
2. NIH   - 55,000,000 Unique Monthly Visitors 
3. Yahoo! Health   - 50,500,000 Unique Monthly Visitors 
4. MayoClinic   - 30,000,000 Unique Monthly Visitors
5. MedicineNet    - 25,500,000 Unique Monthly Visitors
6. Drugs    - 22,000,000 Unique Monthly Visitors 
7. Everyday Health   - 18,000,000 Unique Monthly Visitors 
8. HealthGrades    - 17,000,000 Unique Monthly Visitors 
9. Healthline   - 16,000,000 Unique Monthly Visitors 
10.Mercola    - 15,500,000 Unique Monthly Visitors 
11.Health    - 15,000,000 Unique Monthly Visitors 
12.MindBodyGreen   - 10,500,000 Unique Monthly Visitors
13.Medscape   -  9,000,000 Unique Monthly Visitors 
14.RxList   -  7,000,000 Unique Monthly Visitors
15.MedicalNewsToday   -  6,500,000 Unique Monthly Visitors