Giles, 37, is hitting .296 with a .391 on-base percentage, 61 walks and 44 strikeouts this season.
Boston's interest in Giles might be spurred by concern about the health of third baseman Mike Lowell, who is battling a sore hip, and designated hitter David Ortiz, who has spent time on the disabled list resting a torn tendon sheath in his left wrist.
Giles is earning $9 million this year, and his contract with the Padres has a club option for $9 million for 2009 that would climb to $11 million in the event he is traded.
Giles has a limited no-trade clause, and Boston is among the teams to which he cannot be traded without his permission.
Joe Bick, his agent, declined to discuss the situation.
Buster Olney is a senior writer for ESPN The Magazine.