Infinity Ward studio, owned by Activision, has confirmed that Call of Duty 4: Modern Warfare has sold over 10 million copies worldwide.
Studio head Vince Zampella has said he doesn't know the numbers for the platform-specific sales, but he did say that the game has been most successful on Xbox 360.
Call of Duty 4 was released on PC, PS3 and Xbox 360 last November. It is so popular with gamers that it still commands a top 10 place in the UK All-Formats chart, holding on at nine for the week just passed.
Infinity Ward say Call of Duty 4 is one of less than ten games to reach the double figures milestone since 2000.
As for Call of Duty 5, Activision have still not announced which franchise regular will be developing the game, Treyarch or Infinity Ward. Rumours have suggested the former, but after the success of COD4, we're keeping our fingers crossed for IW.