The cannabinoid receptor CB2 is highly expressed in immune cells suggesting an important role in numerous diseases such as inflammation, cancer, osteoporosis and liver diseases relating to modulation of the immune system. As a consequence, activation of receptor CB2 is a promising therapeutic strategy for the treatment of a large range of diseases. Indeed, selective CB2 agonists display beneficial anti-inflammatory, anti-cancer and antifibrogenic properties and positive effects on liver disease and osteoporosis. This article reviews the CB2 involvement in the immune system and the promising therapeutical potential of selective CB2 agonists in the treatment of several immune-related diseases.