Although several studies have investigated the psychological and physical predictors of success in sport, little is known about the potential biochemical correlates of winning in sporting competitions. In various species, competition appears to elicit a hormonal response according to its outcome, defeat or victory. Given its importance in social dominant behaviour and aggressiveness, several studies have focused on testosterone (T) variation after competition. In humans, aggression and competition between groups are ubiquitous and represent an important aspect of modern societies. However, it is extremely difficult to investigate the hormonal changes that underpin the response to victory or defeat in real life. In this regard, games of sport may represent an ideal ecological experiment for studying hormonal changes according to the competition's outcome. In this review, we provide an overview of T changes after winning or losing different types of sporting challenges. Additionally, critical issues for future studies will be discussed.