Substance : Proviron (mesterolone) is an interesting anabolic steroid, though it is not of much value to bodybuilding. It seems that the most common reason for many to consider including it in a steroid stack is for anti-estrogenic activity. In the days before anti-aromatases and the use of SERMs (selective estrogen receptor modulators) such as Clomid and Nolvadex, there was some merit to this.
Description : Proviron is the brand name for the orally applicable androgen and DHT (dihydrotestosterone) derivative called Mesterolone. Roughly 5% of testosterone undergoes 5-alpha reduction to form the potent androgen DHT, which is a sex hormone and androgen hormone. DHT plays a major role in the formation of the male genitals, and, in adults, it acts as the primary androgen in the prostate and hair follicles. Proviron is almost as pure a DHT steroid as you will find out there. With DHT compounds such as proviron, you need not worry about any estrogen aromatization.