Patch 1.03 tweaks the Inferno difficulty level, fixes countless bugs and adjusts the availability of high-end items to promote a wider variety of play styles.
The developer has also lowered Blacksmith and Jeweler costs, increased level 60 repair costs, and added bonus damage to enemies when playing as a group.
Individual character classes have their own range of new skills and damage caps, while the effectiveness of boss spells has been increased or reduced depending on the difficulty level.
Diablo 3 went offline at 2am (BST) in order to deploy the new patch, which is detailed in full on Battle.net.
Blizzard recently introduced real-money auction houses to Diablo 3, as well as an update that will optimise the game for use on the new MacBook Pro line with Retina displays.
Diablo 3 launched last month. The game is free to users who sign up for the World of Warcraft annual pass, a yearly subscription to the popular MMO.
A Starter Edition of the game has also been confirmed, offering a limited introduction to Diablo 3 with content similar to its private beta.
> Read Digital Spy's Diablo 3 review
Watch the Diablo 3 launch trailer below: