Reed was shut down after being examined by hand specialist Dr. Andrew Weiland.
The 33-year-old started Sunday's game against Los Angeles but left in the second inning after delivering a pitch. The Mets lost 14-3.
"It's disappointing," said Reed, who is 10-4 after his seven-game winning streak was stopped by the Dodgers. "I wanted to help the team win and now I'm on the shelf for 15 days."
Reed has a 4.94 ERA in 21 starts.
Mets closer John Franco has missed the last five weeks with a partially torn tendon on his middle finger. Reed's injury was not as serious.
"John's was 100 times worse than mine," Reed said.
The Mets recalled right-hander Dan Murray from Triple-A Norfolk to take Reed's spot on the roster. Murray was 11-7 with a 4.92 ERA with Norfolk.
Reed first noticed the injury last Monday in Milwaukee. He also had a bump that developed on the finger, but it was unrelated to his injury.
Reed will not pick up a ball for 10 days. He'll test the finger after the period of rest.
"We lost Rick Reed, and he has has been a major part of our team for the last few years," Mets manager Bobby Valentine said. "It might just be nature's way of telling Rick Reed he'll be rested at the end of the season."
With Reed out, Valentine said Masato Yoshii will return to the rotation and will start Friday in San Francisco. Yoshii was moved to the bullpen because the Mets had six healthy starters.
Sidelined pitcher Bobby Jones made a minor league rehab start Saturday and could return from his shoulder injury soon.
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