Endogenous opioids are responsible for diverse physiologic actions through activation of specific receptors. Acute consumption of opioids has no serious complication. Chronic use of opioids though is accompanied by tolerance to some effects (such as constipation, nausea and dry mouth), it leads to addiction and brain dysfunction. On the other hand, stopping the chronic use of opioids causes withdrawal signs (including sweating, anxiety, nausea, muscular pain, insomnia, diarrhea, agitation and hot flush) without get rid of psychological dependence. It is well known that exercise activities (EAs) are associated with euphoria and delight through activation and release of endogenous opioids. Therefore, EAs can be effective in prevention and treatment of addiction. Beta-endorphin is one the most important endogenous opioids. It is an endogen neuropeptide with narcotic properties that is found in central and peripheral nervous system. Despite numerous studies on the effects of EAs on beta-endorphin, understanding impact of the different types of EAs on beta-endorphin and other endogen opioids requires further studies. In this article acute and chronic effects of EAs on beta-endorphin are reviewed. It is well accepted that acute and chronic EAs increase beta-endorphin level. Mechanism(s) responsible for rising beta-endorphin after acute and chronic EAs are somewhat different.