The Pew Charitable Trusts said Russia and Ukraine essentially ran down the clock filibuster-style after earlier expressing positive sentiments about the proposal.
"This is a bad day for Antarctica and for the world's oceans that desperately need protection," said Andrea Kavanagh, director of Pew's Southern Ocean sanctuaries project.
The Ross Sea is home to the Antarctic toothfish, a lucrative species that is often marketed in North America as Chilean sea bass.
The nations that make up the Commission for the Conservation of Antarctic Marine Living Resources are scheduled to meet again next October.
Kavanagh said she doesn't believe the sanctuary plan is dead, although she's not sure what it will take now to get it passed.