Ramadan's lawyers had pushed for his release since he was detained on February 2nd, arguing his multiple sclerosis and nerve damage could not be adequately treated behind bars.
The Oxford University professor, a prominent TV pundit whose grandfather founded Egypt's Muslim Brotherhood movement, denies charges that he raped two Muslim women in France.
A court-ordered medical examination last Thursday found that the 55-year-old Swiss academic's condition was compatible with detention.
The day after the test, he was hospitalized for four days due to what his entourage said was a worsening of his condition.
Ramadan has complained that the medical tests were only cursory and that the doctor examining him did not have access to his medical records.
He refused to appear at Thursday's hearing at the main Paris appeals court.
Ramadan's two accusers went to the police in late October, both alleging that he had raped them in French hotel rooms.
Henda Ayari, 41, said she had decided to accuse him publicly after the "Me Too" campaign against sexual abuse and harassment encouraged her to speak out.
Ayari, a feminist activist who previously practised a conservative strain of Islam, says Ramadan raped her in a Paris hotel room in 2012.
The second accuser, an unnamed disabled woman, alleges that Ramadan raped her and beat her in a hotel in the southeastern city of Lyon in 2009.
French authorities ordered Ramadan to be placed in custody after he was charged, judging him a flight risk.
His lawyers have unsuccessfully proposed handing over his Swiss passport, bail of 50,000 euros ($62,000) and daily check-ins at the police station to secure his release.
A professor of contemporary Islamic studies at Oxford, Ramadan has been on leave since November after the allegations emerged.
One of European Islam's best known figures, he has dismissed the accusations against him as a smear campaign by his enemies and his lawyers argue there are inconsistencies in the women's accounts.
His supporters -- including two million Facebook followers -- have lashed out angrily at his arrest, with many complaining that he has been unfairly targeted because he is Muslim.
Ayari was placed under police protection in November after receiving death threats.