The teams reached a tentative agreement Tuesday that would send the 32-year-old pitcher to Atlanta, two people familiar with the deal said, speaking on condition of anonymity because the trade had not been finalized.
That could happen Wednesday. Vazquez must take a physical for the deal to be completed, one of the people said, and he was likely to be examined Wednesday.
It was unclear who the Braves would send to Chicago in exchange for Vazquez. The right-hander was 12-16 with a 4.67 ERA in 33 starts for the AL Central champions this season, surpassing 200 innings for the eighth time in nine years.
The trade agreement was reported earlier by several news outlets.
With obvious holes in the rotation, Braves general manager Frank Wren has said he hopes to add two starting pitchers this winter. Atlanta pursued Padres ace Jake Peavy before Wren said last month "we have moved on and shifted our focus" after San Diego didn't agree to what he called "a strong package of players."
Braves right-hander Tim Hudson had elbow ligament replacement surgery on Aug. 7. Aging veterans John Smoltz and Tom Glavine also had season-ending arm operations, and their status for 2009 remains uncertain. Both are free agents.
Left-hander Mike Hampton reached a tentative agreement to sign with Houston.
Vazquez's future prospects with the White Sox appeared dim after manager Ozzie Guillen said in September that he wasn't a big-game pitcher. In his last three regular-season starts and the playoff opener against Tampa Bay, Vazquez was 0-4 with a 13.22 ERA.
Vazquez has a 127-129 career record with Montreal, the New York Yankees, Arizona and the White Sox.