The Braves purchased the contract of right-hander Kris Medlen from Triple-A Gwinnett to start Thursday night's game against Colorado. They recalled infielder Diory Hernandez from Gwinnett.
Infante broke a bone in his left hand during Wednesday night's game against the Rockies and Reyes strained his right hamstring.
Infante is expected to be out at least six weeks with a broken fifth metacarpal. He got hurt when he was hit by a pitch from Manny Corpas.
Manager Bobby Cox said Infante was expected to have surgery on Friday. Infante sustained a similar injury before the 2008 season.
Infante made 14 starts as the Braves' leadoff hitter. His two hits Wednesday night raised his average to .349 with one homer and 11 RBIs.
The versatile Infante began the season as a utility player, but he was earning increase starts at second base in recent weeks, pushing Kelly Johnson to the bench. He also made fill-in starts at shortstop and third base and appeared in three games in the outfield.
"He was forcing our hand to get him in there more and more and more," Cox said Thursday. "It was a big loss for us."
Hernandez hit .355 with 20 RBIs in 29 games for Gwinnett. Medlen was 5-0 with a 1.19 ERA in eight games for Gwinnett.
Reyes is 0-2 with a 7.00 ERA in six games, including five starts.