Red Dead Redemption has sold over five million copies worldwide since it released on May 18 in US (May 21 in UK).
The news comes as part of Take-Two Interactive's investors call currently underway.
The firm said it's "conservatively" expecting the open-world cowboy shooter to enjoy a "long tail" of sales, with the support of DLC content being released throughout the summer, starting with the 'Outlaws To The End' pack releasing June 22, which adds six new co-op missions to the game.