Subscriptions to the popular fantasy RPG World of Warcraft have dropped by 800,000, from 11.1 million three months ago to 10.3 million.
In a conference call to discuss Activision's third quarter sales figures, Blizzard CEO Mike Morhaime suggested that the biggest losses were being seen in China.
He then added that World Of Warcraft is "one of the most popular online games in China, and remains by far the most popular subscription-based MMO in the world."
He also admitted that the company was aware that improvements could be made to the MMO, and spoke about a new update that was due in coming weeks, which would feature new content and raids.
"It's really not intended to go out and drive new user acquisition, that's a whole other strategy," he explained.
"But it does drive engagement with the game, and so that will impact churn if we do it successfully, and will eventually drive winback, as players tell each other about the content they're enjoying."
The game is used to highs and lows when it comes to subscribers, with numbers falling as players complete new content, and rising again on the release of a new expansion. The latest update, Mists Of Pandaria, was recently announced at Blizzcon.
The plan to include Diablo III access with World Of Warcraft annual passes should also act as a stimulus. The release date for Diablo III was not confirmed in the call beyond 2012.