Serial sex offender Robert John Fardon remains in a Brisbane hospital ahead of a hearing that will determine if he'll again be released from jail.
The serial sex offender was admitted to the Princess Alexandra Hospital on Sunday night for a medical assessment, a Corrective Services spokesman told AAP.
He could not comment on the nature of Fardon's medical condition.
Fardon was released from jail into supervised emergency accommodation on Friday, after Supreme Court judge Peter Lyons refused an application to delay his release.
But he was back behind bars just two hours later after Attorney-General Jarrod Bleijie sought an urgent hearing in the Court of Appeal.
The appeals court ordered the warrant be issued for Fardon's arrest and he was back behind bars on Friday night.
Fardon will remain in custody until Wednesday, when an appeal against the decision to free the sex offender will be heard.
If he is released from hospital before then, he'll be returned to the Wolston Correctional Centre.
Fardon has spent most of his adult life in prison for sex offences against women and girls dating back to 1967, when he was 18.
He has been serving an indefinite jail term for his crimes.
But Justice Lyons ruled last week that he should be freed, saying any risk he might pose to the community could be managed by strict supervision orders.
Mr Bleijie disagrees and has vowed to exhaust every legal avenue to keep Fardon locked up.