Pain in the knee caused the seven-year veteran to miss the team's training camp practice at Jackson, Miss., Saturday. He had knee fluid drained Friday.
"Anytime you're coming off of a major surgery, you're optimistic and hopeful," Coach Sean Payton told reporters. "It's just managing the injury and we'll get a little bit further look with his MRI just to see where it's at and go from there."
The 29-year-old Ole Miss product missed the Saints' final 13 games last season with a similar injury, and in 2005, he missed the final 11 games because of torn right knee ligaments.
Despite his knee injuries, McAllister is the first running back in club history to rush for at least 1,000 yards in each of four seasons.
His single-season high came in 2006 (1,057 yards on 244 carries with 10 touchdowns).