The two-time Pro Bowler, who had expressed dissatisfaction with his contract in offseason interviews, did not report for a physical or the 1 p.m. team meeting that kicked off camp at the Timex Performance Center.
General manager Jerry Reese did not want to discuss Umenyiora's absence.
"I'm not taking any questions about Osi," Reese said at his news conference. "Osi's not here. He knows training camp opens today. He's not here. I just really want to talk about the guys that are here. That's really what's most important. I can't control guys that are not here."
Neither Reese nor Coach Tom Coughlin has spoken to Umenyiora since the lockout ended.
"What I would like to see happen is obviously Osi come in, sit down and talk to Jerry and then decide he wants to be a Giant and make a difference on our team," Coughlin said. "Osi is an excellent player, he's part of our team, he's under contract, he gives us an outstanding chance to win. The more outstanding players we can have the better."
The Giants also signed seven of their eight draft choices (the team is still negotiating with No. 1 pick Prince Amukamara), released defensive tackle Rocky Bernard and placed wide receiver Ramses Barden on the active/physically unable to perform list.
Reese expects Amukamara to soon join the team.
"I don't expect to have a long holdout," Reese said. "There are (some) language issues we need to resolve, but I don't anticipate a holdout."
Wait, there's more. Running back Brandon Jacobs restructured his contract, unrestricted free agents Mathias Kiwanuka and Kevin Boothe rejoined the team, as did two exclusive rights free agents, tight end/fullback Bear Pascoe and offensive lineman Jamon Meredith.
Because of the transition rules relating to the new CBA, none of those players are permitted on the practice field until Aug. 4. The Giants will hold their first practice tomorrow evening.
The draft choices who signed contracts were defensive tackle Marvin Austin from North Carolina (second round), wide receiver Jerrel Jernigan from Troy (third), offensive lineman James Brewer from Indiana (fourth), linebacker Greg Jones from Michigan State (fifth), safety Tyler Sash from Iowa (sixth), linebacker Jacquian Williams from South Florida (sixth) and running back Da'rel Scott from Maryland (seventh).
Bernard played two seasons for the Giants after signing as a free agent in 2009 following seven seasons with the Seattle Seahawks.
In those two years, Bernard played as a reserve in 29 games. He had 61 tackles (39 solo) and 3.0 sacks. In 2010, Bernard played in 14 games and contributed 26 tackles (18 solo) and 2.0 sacks (at Minnesota and vs. Philadelphia).
Barden is entering his third season. He suffered a fractured ankle in a game against Dallas last Nov. 14 and subsequently underwent surgery. Barden was placed on injured reserve two days later.
Before his injury, Barden had played in six games and caught five passes for 64 yards. His best game was the one in which he got hurt; he had three receptions for 34 yards, including a career-long 26-yarder, against the Cowboys.
*The Giants currently have 77 players in camp.