Two inmates have died in custody on consecutive days at a prison criticised for its "appalling" death rate.
The Prison Service said Wyndham Thomas, 41, died on 6 November and George McCallum, 79, a day later.
A spokeswoman said there would be investigations by the Prisons and Probation Ombudsman but did not reveal any further details.
Eight Nottingham Prison inmates killed themselves between February 2016 and January 2018.
The Chief Inspector of Prisons, Peter Clarke, described the suicide rate at Nottingham as "tragic and appalling" in a report published in March.
Inmate Robert Frejus, 29, died in October but the cause has not yet been revealed.