The Arthur Gorrie Correctional Centre in Brisbane’s south-west is in lockdown after a 27-year-old prisoner on remand for rape was found dead in his cell.
A Corrective Service’s spokesman says the man’s death does not appear to be suspicious.
It is the third death in custody in Queensland in the last month.
Another prisoner was found dead in a cell at Brisbane’s Wolston Prison on Tuesday.
The 42-year-old was serving a six-year sentence for child sex offences and had been in jail for 11 months.
Corrective Services said there were no suspicious circumstances in that case either.
The death has been referred to the coroner and to the chief inspector of prisons.
Last week, protesters gathered outside Parliament House in Brisbane to accuse prison authorities of failing to help a seriously ill Indigenous teenager who died while on remand for stealing a car.
Sheldon Currie, 18, was found on his face in his cell by an inmate at the Arthur Gorrie Correctional Centre.
He spent four days in intensive care at Princess Alexandra hospital before dying on February 20.