Online gambling has different regulations in different countries. While it is legal in some nations, there are many that are opposed to online gambling. So, it basically depends on where you are and the rules in that land. There is no specific rule about the legality of bitcoin gambling. If gambling is legal in your country, you can gamble with bitcoins without any restrictions. If online gambling is illegal in a land, bitcoins
give you the benefit of anonymity. However, the users can be traced by the IP address.
Several nations have banned online gambling in their respective countries while in some countries the authorities have not taken any clear stand. Bitcoins are accepted as cash in several casinos in the USA. However, banking system cannot be used for gambling purposes there and some states have made gambling illegal both online and offline.
It can be concluded that where governments do not recognize bitcoin as a currency, restrictions and laws applying to online and mobile gambling are extended to bitcoin gambling. If online gambling is illegal, bitcoins gambling too is illegal.