Raloxifene hydrochloride (trade name Raloxiheal) is very new anti-estrogenic drug on the prescription market, and it is a member of the category of drugs known as selective estrogen receptor modulators (SERMs), which is actually a sub-category of an even broader category of drugs known as anti-estrogens. The sub-category under anti-estrogens are aromatase inhibitors (AIs), which include the three most common: Aromasin (Exemestane), Arimidex (Anastrozole), and Letrozole (Femara), though there are plenty of other aromatase inhibitors in existence as well. SERMs and AIs are what make up the broad class of anti-estrogens. SERMs and AIs differ quite greatly in terms of their mechanisms of action and how they operate physiologically. As with any profile covering SERMs and AIs, the difference between these two classes of anti-estrogenic drugs must be boldly stated and clarified before moving on to discussing Raloxifene in particular.