The Medical Letter on Drugs and Therapeutics is an independent, peer-reviewed, nonprofit publication that offers unbiased critical evaluations of drugs, with special emphasis on new drugs. It evaluates virtually all new drugs and reviews older drugs when important new information becomes available on their usefulness or adverse effects. The Medical Letter is published every other week in a four-page newsletter format and is available in print, Palm OS, and online versions. The newsletter carries no advertising and is supported entirely by subscription fees. A typical issue appraises two or three new drugs in terms of their effectiveness, toxicity, cost, and possible alternatives. Occasionally, The Medical Letter publishes an article on a new non-drug treatment or a new diagnostic aid.

The Medical Letter is intended specifically to meet the needs of the busy health care professional who wants unbiased, reliable, and timely information on new drugs. The Medical Letter indicates whether a new drug offers genuine advantages over older drugs, whether its effectiveness is limited, or whether it is too toxic or too expensive to justify its use. If new information changes the picture, follow-up reports are published.