Abstract: An online gaming multicast service system includes a set of interconnected multicast managers (MM1, MM2, MM3) for receiving messages from game servers (GS1, GS2) to end-users (A-H). Each message and an associated end-user recipient list ({B,E,F}, {A,G,H}) is received by one of the multicast managers. The multicast service system further includes a set of multicast servers (MS1, MS2, MS3), one multicast server being connected to each multicast manager, for distributing each message to all end-users in the associated end-user recipient list. Each multicast manager includes means for determining which recipients in an end-user recipient list associated with a message are connected to which multicast server and for dividing the end-user recipient list into corresponding end-user recipient sub-lists.