eBizMBA has ranked the top 20 health information websites using Quantcast and Compete data. The Top 20 are:

1 WebMD.com
2 NIH.gov
3 MedicineNet.com
4 MayoClinic.com
5 Yahoo! Health
6 RightHealth.com
7 Drugs.com
8 RxList.com
9 RealAge.com
10 MedHelp.org
11 Healthline.com
12 EverydayHealth.com
13 Wrongdiagnosis.com
14 Healthgrades.com
15 Wellsphere.com
16 FamilyDoctor.org
17 QualityHealth.com
18 HealthCentral.com
19 Prevention.com
20 Health.com

It’s interesting to note that Health.com, at #20, gets 935,000 monthly visitors according to Compete. Basically, takes over a million visitors a month to  make the list and that still doesn’t guarantee you’ll make money using a web ad model.