Over 1.3 million users downloaded the demo in its first three days. The game was initially available only to paying Xbox Live Gold members, becoming available to all members on January 29.
Microsoft said 53 percent of Xbox Live Gold members downloaded the game in Japan, where the Resident Evil franchise is known as Biohazard.
The demo is now also available on PlayStation Network.
Resident Evil 5's release is slated for March 13.