Yastrzemski's family released the following statement: "Carl Yastrzemski arrived at Massachusetts General Hospital on Monday after experiencing chest discomfort. After numerous tests and evaluations, it was determined that he needed triple bypass surgery, which was performed this afternoon. The surgery was a complete success and he is resting comfortably. We are most grateful for all of the prayers and support we have received."
Yastrzemski, who is Major League Baseball's last Triple Crown winner, will turn 69 on Friday. He won his Triple Crown in 1967, Boston's "Impossible Dream" season.
There had been no recent reports of any health problems for Yastrzemski.
"I haven't seen him in so long," said Jerry Remy, the NESN analyst who was a teammate of Yaz's from 1978-83. "I see him maybe twice a year at the ballpark. I know he had been walking, and he plays golf."
Yastrzemski, a first-ballot Hall of Famer who played his entire career with the Red Sox, is the club's all-time leader in several offensive categories.
"As a kid, the '67 team was the team I watched," said Remy, a Massachusetts native. "He was the Triple Crown winner. Then having a chance to play with him, it was at the tail end of his career. Personally, I got along very well with him. He was pretty much to himself. One thing, until the day he retired, he refused to miss a fastball. He would not miss a fastball."
An 18-time All-Star, Yastrzemski began his career by replacing the retiring Ted Williams in left field. After struggling out of the gate amid that enormous pressure, Yaz eventually created a legacy of his own.
Fellow Hall of Famer Jim Palmer -- the former Orioles great -- remembers the challenge that came with facing Yastrzemski.
"It wasn't pleasant," Palmer said. "He was a high-ball hitter. Most left-handed hitters like the ball down. He could run the bases, he could hit home runs, he could hit for average, he could hit your best pitch, he could hit your worst pitch. Until late in his career, I don't think we ever got him to take a bad swing at any pitch we ever threw. Obviously, he was a very tough out."
Ever since his retirement, Yastrzemski has kept a low profile. He always comes to Red Sox Spring Training as a special instructor, but prefers to work in anonymity with young prospects rather than be a presence at Major League camp.
"He came to camp a couple of years ago," said Red Sox manager Terry Francona. "I guess he was never real big on that. He always wanted to stay on the Minor League side. But he came over for a couple of weeks a couple of years ago. I can't say I knew him real well. I was glad he did it. I thought it was kind of an honor for us. I know the guys enjoyed it. He'd go hang out in the cage. But every time I've seen him, he's been very, very nice."
Yastrzemski won three batting titles in his illustrious career, clubbing 452 home runs and producing 1,844 RBIs. He had 3,419 hits while batting .285. On defense, Yaz was a maestro in left field, playing the caroms of the Green Monster to near perfection at a time the wall was covered by tin instead of the padding it currently has.
Yaz's No. 8 is on the right-field facade at Fenway Park, along with the numbers of Williams, Carlton Fisk, Bobby Doerr and Joe Cronin.
Ian Browne is a reporter for MLB.com. Material from the Associated Press was used in this report. This story was not subject to the approval of Major League Baseball or its clubs.