"Over the last few weeks, while preparing for the 2007 season, my body has not responded as it has in years past," Foulke said in a statement. "I feel strongly I will not be able to perform at the level where I need to be to help the Indians this season. They are a class organization and I wish them the best of luck in 2007."
The Indians, whose slide from 93 wins in 2005 to 78 wins and a fourth-place finish last season was tied to a dreadful bullpen, signed Foulke to a one-year, $5 million contract in January.
The club would have had to honor that deal if Foulke had reported to camp and then retired.
"He didn't want to disappoint the organization or his teammates," general manager Mark Shapiro said, praising Foulke's integrity.
Foulke had battled elbow, back and knee injuries the past two seasons. Last year he was replaced as Boston's closer by rookie Jonathan Papelbon. The 34-year-old recently had elbow soreness and informed the Indians of his decision Thursday when the club's pitchers and catchers reported to Winter Haven, Fla.
Foulke was one of five relievers signed this winter by Shapiro, whose goal was to add experience and back-end depth to a Cleveland bullpen which posted a major league-low 24 saves last season.
Foulke's retirement means Borowski, signed in December to a $4.25 million, one-year deal, will begin the season as the Indians' closer. Borowski had 36 saves in 43 chances last season for Florida.
Interestingly, Borowski signed with the Indians after the Philadelphia Phillies backed out of a preliminary agreement with the 35-year-old because of concerns over medical tests on his right shoulder.
Shapiro, who also signed relievers Roberto Hernandez, Aaron Fultz and Cliff Politte this winter, said Borowski's health is fine but losing Foulke so quickly was a surprise.
"It's a blow to our depth," Shapiro said. "We knew there was risk involved in a number of guys we signed. It's disappointing, but at the same time we prepared to make adjustments in personnel, we're just making them faster than we had to."
Shapiro said the club may use the money saved by Foulke's retirement to find more late-inning relief help. In the short term, the chances of Matt Miller making the Indians' opening-day roster improved. Miller missed most of last season following elbow surgery.
Foulke went 3-1 with a 4.35 ERA but no saves in 44 games in 2006, and he missed two months with elbow tendinitis.
A stretch of 11 straight scoreless appearances in September gave the Indians hope he could fix their problems at closer. Foulke passed a physical with the club in January.
The Indians had planned to have Foulke and Borowski go head-to-head for the closer's role this spring. Foulke figured to have an edge because of his 190 career saves, track record and postseason experience.
Cleveland has struggled to find someone to pitch in the ninth inning since trading Bob Wickman to Atlanta before the July 31 deadline last season. Wickman had 15 saves before he was dealt, and in the season's second half, Cleveland used Rafael Betancourt, Fausto Carmona and Mastny to finish games _ with mixed results.
In 2004, Foulke helped the Red Sox win their first World Series since 1918.
After saving 32 games during the regular season, Foulke went 1-0 with three saves and a 0.64 ERA in 11 postseason appearances. In Boston's sweep of the St. Louis Cardinals in the World Series, Foulke closed all four wins.
In the ninth inning of Game 4, Foulke retired Scott Rolen on a fly ball, struck out Jim Edmonds and then gloved Edgar Renteria's comebacker beore throwing to first baseman Doug Mientkiewicz for the series-ending out.
Foulke, who went 41-34 with 3.30 ERA in 588 career appearances, also pitched for San Francisco, the Chicago White Sox and Oakland. He was an All-Star in 2003 when he led the AL with 43 saves for the Athletics.