The convicted mass murder's lawyer has indicated they may appeal to the European Court of Human Rights
Anders Breivik's human rights were not violated by isolating him in prison and his appeal has been rejected, Norway's top court has said.
The far-right terrorist claimed being in solitary confinement in "inhumane" conditions had seriously damaged him and made him even more radical in his views.
The Norwegian supreme court, however, has now upheld a ruling made by the court of appeal in January.
The court said there was "no basis" for a different conclusion.
Following the latest judgment, Breivik's lawyer, Oystein Storrvik, said he will take the case to the European Court of Human Rights in Strasbourg.
Mr Storrvik said: "We've always been prepared for the possibility that our case before the Norwegian courts may not succeed."
Last year, the country's government had appealed a lower court ruling that Breivik's isolation behind bars violated his rights.
He is currently serving a 21-year jail term for killing 77 people in a bomb and gun attack in 2011.