World of Warcraft lost 1.3 million subscribers during the first three months of this year, Activision Blizzard has revealed.
The company said that 14 per cent of users left the game. The majority of those were from Eastern countries such as Japan, China, and South Korea.
The latest expansion pack Mists of Pandaria was released last year. That failed to stem the flow of players out of the game.
Activision Blizzard warned investors that it expects subscriber numbers to continue falling.
Chief executive Bobby Kotick blamed the rise of free to play games for the fall in the number of subscribers.
"It's important to note that the nature of online games has changed, and with the environment becoming far more competitive," he told investors.
The game was launched eight and a half years ago in November 2004. Four major expansions have been released since.
Kotick hinted that there may be many more in the pipeline, and that they will come much more frequently than in the past.
"To address this, we're working to release new content more frequently to keep our players engaged longer and make it easier for lapsed players to come back into the game."
In 2011, Blizzard introduced some elements of free to play into the game. New players can play the game up to level 20 before they need to subscribe.