Tight end Rob Gronkowski also was not present at Monday's OTAs, a source told ESPN's Mike Reiss. Gronkowski has previously committed to playing for the Patriots in 2018.
Brady has regularly participated in the Patriots' voluntary OTAs in the past. He has skipped all of the team's offseason program so far this season.
Brady, 40, previously explained his decision to miss earlier portions of the offseason program as being based on family while also helping him be "really rejuvenated" for the 2018 season. Offensive coordinator Josh McDaniels noted on May 11 that the coaches would like all players at the workouts but that they understood the quarterback's decision because the sessions are voluntary.
The three-time MVP committed to playing the 2018 season during an appearance April 30 at the Milken Institute Global Conference in California.