"We're putting in a lot of time and effort to get a deal done," Giles' agent, Joe Bick, said by phone from Cincinnati on Monday.
Bick declined to divulge details.
Padres general manager Kevin Towers also said the sides were nearing a deal.
The Giles brothers grew up in El Cajon, just east of San Diego.
Brian Giles, the Padres' right fielder, came over in a trade with Pittsburgh on Aug. 26, 2003.
The Braves declined to offer Marcus Giles a contract last week, deciding they could no longer afford him under their tightening budget.
The 28-year-old Giles made the All-Star Game in 2003, his first full season as a starter. He wound up hitting .316 with 21 homers and 69 RBIs -- all career highs.
But Giles was plagued by injuries and clearly uncomfortable when the Braves moved him into the leadoff spot for 2006, seeking a replacement for Rafael Furcal. The second baseman slumped to .262 with 11 homers, 60 RBIs and 10 stolen bases, his disappointing season coinciding with the end of Atlanta's record streak of 14 straight division titles.
The Padres traded second baseman Josh Barfield to the Cleveland Indians for infielder Kevin Kouzmanoff and right-hander Andrew Brown. Kouzmanoff is expected to play third.
The Padres also held onto second baseman Todd Walker when he accepting the team's offer of salary arbitration last week.