Some bodybuilders and athletes use trenbolone esters for their muscle-building and otherwise performance-enhancing effects.  Such use is illegal in the United States and many other countries. The DEA classifies trenbolone and its esters as Schedule III controlled substances under the Controlled Substances Act .  Trenbolone is classified as a Schedule 4 drug in Canada  and a class C drug with no penalty for personal use or possession in the United Kingdom .  Use or possession of steroids without a prescription is a crime in Australia . 
Anabolic androgenic steroids (AAS) were initially created for therapeutic purposes, and synthetic derivatives of the male hormone testosterone. Due its great anabolic effects, these drugs are being used on a large scale, for the improvement of sports performance. In this present study, we aim to show the history of it’ use, present their mechanisms of action, more particularly its use correlate with improved body composition, muscle mass, aerobic capacity and verify their possible side effects, analyzing their use therapeutic and indiscriminate, through direct scientific research with the sports. Sources were reviewed scientific the following search engines: PUBMED, LILACS and SCIELO. The results showed that in presence of a suitable AAS and diet can contribute to increases in body weight, particularly lean body mass and muscle strength gains achieved by high intensity exercise, these effects can be further potentiated, the use of supraphysiological doses, but in the aspect of aerobic power, there are not scientific evidence to support their improvement. Regarding side effects, the use of AAS, is related to several complications in the liver, cardiovascular system, reproductive system and psychological characteristics, always assigned by the non-therapeutic and abuse of AAS. Thus we conclude that the use of AAS, are directly linked to gains muscle mass, strength, as well several side effects, always assigned to abusive and indiscriminate doses, it is noteworthy that the scientific literature, still has a certain lack of studies, mainly randomized, controlled, with supraphysiological doses in human, so many effects are still unknown.