A US court has rejected an appeal by the parents of a brain-damaged woman to order doctors to resume feeding her.
Mrs Schiavo's husband has fought to have the feeding tubes removed
Terri Schiavo, 41, who has been in a vegetative state since 1990, has received no food or water since Friday.
The three-judge panel in Atlanta, Georgia, ruled 2-1 to deny the parents' appeal, a day after a judge in Florida also refused a similar request.
A lawyer representing her parents, Bob and Mary Schindler, said they would file another appeal.
Mrs Schiavo's feeding tube was removed at the request of her husband, Michael Schiavo, who says she would not want to be kept alive artificially and has no hope for recovery.
Mr Schiavo and the Schindlers have been locked in legal battles for years over whether the feeding tube should be removed.
Series of appeals
A panel of three judges from the 11th Circuit Court of Appeals had to consider whether to order the reconnection of Mrs Schiavo's feeding tubes to allow her to remain alive while the legal wrangling continues.
TERRI SCHIAVO CASE
Feb 1990: Mrs Schiavo collapses
May 1998: Mr Schiavo files petition to remove feeding tube, triggering legal battle
Feb 2000: Court rules to remove feeding tube
Oct 2003: Florida's lower house passes "Terri's Law", allowing governor to order doctors to feed Mrs Schiavo
Sept 2004: Florida Supreme Court strikes down law
Dec 2004: Case goes to US Supreme Court
Jan 2005: Court rejects petition
18 Mar 2005: Florida court again allows removal of tube
22 Mar 2005: Federal judge turns down parents' appeal
23 Mar 2005: Appeals court backs federal ruling
But it ruled that Mrs Schiavo's parents had failed "to demonstrate a substantial case" for success, should they be allowed to take to court their claim that their daughter's religious and due process rights had been violated.
The decison comes a day after a judge ruled the Florida courts had not violated Mrs Schiavo's rights by ordering her feeding tube to be disconnected.
The BBC's Lesley Curwen in Washington says it is uncertain whether the Schindlers' next appeal will be heard at a local level or whether it will go to the highest court in the land, the Supreme Court.
However, the Supreme Court has previously refused to intervene in the case.
The family claim that Mrs Schiavo is fading fast, our correspondent adds.
Before the latest decision was handed down, Mrs Schiavo's mother made an emotional appeal for the Florida Senate to intervene, saying: "For the love of God, don't let my daughter die of thirst."
Schindler family supporters have protested against the rulings
A lawyer for Mr Schiavo said Terri was "stable, peaceful and calm".
Before the Schindlers filed their latest appeal, Mr Schiavo urged the Atlanta court not to rule in favour of reconnecting the tubes.
"That would be a horrific intrusion upon Mrs Schiavo's personal liberty," his lawyer, George Felos, wrote to the judges.
Congress and President George W Bush intervened over the weekend to allow federal courts to review the case.
The debate over the case has divided the US, with some arguing Mrs Schiavo's life must be preserved and others condemning politicians for interfering in a private family affair.
It is thought Mrs Schiavo could survive for up to two weeks before dying of starvation.