Last week, 69 people fled from a police detention centre on the jail's outskirts via a tunnel dug from the jail's courtyard.
This time, 48 prisoners of the Benfica jail in the northern part of Rio made a hole in the ceiling of the cellblock, and used a rope to climb down the wall of the jail before dawn.
Authorities say they suspect guards had been paid to turn a blind eye, as a turret on the wall was not staffed during the escape.
The guards are now under arrest.
Corruption is widespread in Brazilian prisons as guards are poorly paid, while powerful drug gangs often use money and intimidation to free their comrades.
By Just Us 11 October 04
