What is Winstrol steroid? Winstrol steroid is the brand name for the anabolic steroid Stanozolol. It is a synthetic steroid derived from dihydrotestosterone (DHT), and it was first developed in the 1960s by Winthrop Laboratories. Winstrol is known for its anabolic effects, which can increase muscle mass, strength, and endurance. It is commonly used by bodybuilders and athletes to improve their …