The article deals with the problem of competitive balance on the professional sports market, one of the most important issues linked with the functioning of sports organizations. The competitive balance effect has a major influence on the performance of sports organizations in terms of both their sports results and finances. The term competitive balance means an equal level of sports clubs taking part in competitions in a specific type of sport. An important feature of sports clubs working as business enterprises is that their main product is a sports show, and that the result of this show—in other words the winner of a match—is difficult to predict. This uncertainty of outcome attracts audiences and makes people buy these sports products. The author sets out to show that competitive balance helps increase the revenue of individual sports clubs and leagues. This applies to revenue generated from both individual buyers (supporters) and institutions. As a result, clubs earn more money from the sale of tickets, club merchandising and advertisements, and they also increase their income from sponsors and the sale of broadcasting rights to the media. Sports leagues in which there is a lack of competitive balance between individual clubs are vulnerable to various kinds of threats, including indebtedness resulting from growing costs of buying new players. Weaker clubs may face the danger of bankruptcy, while stronger clubs may be tempted to withdraw from the league and compete elsewhere. This explains why organizations managing professional sports leagues usually make every effort to maintain competitive balance among sports clubs, Sznajder concludes.