A Medicare Rx plan will not help you very much if it doesnt cover the prescription drugs youre taking right now. Every plan maintains a formulary, which is a list of drugs that you can get for a lower co-pay. If your drugs are not on a plans formulary, consider another plan. Another way to compare formularies is to see how many of the top 100 most-prescribed drugs they cover. A list of these drugs is included on this website.  The Federal Medicare website has a formulary finder at www.medicare.gov, which allows you to enter all of your drugs and search which plans will cover them .