Please click here to go directly to the Drivers & Software area for the EOS Rebel T3i. In the Firmware section, you should see two options:

v101-t3i-600d-x5.dmg (for Mac OS X)
v101-t3i-600d-x5.exe (for Windows)

Click to download the version you need based on your OS. The firmware upgrade procedure is the same as previous upgrades for EOS cameras:

1. Download the zipped firmware file to your hard drive

2. Copy the downloaded .FIR file to an SD memory card by inserting the card into a card reader and dragging/dropping the file to the card

3. Install the SD card into your camera and call up Firmware Ver. x.x.x. in the EOS Rebel T3i's 3rd set-up menu (with the yellow wrench)

4. Select OK when asked if you want to upgrade to the new version

Note that full PDF instructions for the upgrade procedure will accompany the firmware upgrade when you download the zipped file from the site. Be sure to read and thoroughly understand the steps before attempting to install it into your camera.