Nottingham Prison has the highest suicide rate in the country, according to a report from the Prison Reform Trust.
Nottingham Prison had five suicides last year
The report says five people committed suicide at the prison in the past year, one less than in 2002.
Acting governor Karen Lloyd says the jail holds many prisoners on remand - and these inmates are at the highest risk of suicide.
Leicester Prison ranked third in the country for overcrowding.
Ms Lloyd said: "Many of the prisoners have problems with addiction or mental health.
"Most of the distress happens at the time of their initial custody and we try to lessen the distress as much as possible."
About 87% of the prisoners in Leicester are doubling up in single cells because of the lack of space.
Prison Reform Trust director Juliette Lyon said: "Prisoners have to share cells designed for one.
"The jail remains under tremendous pressure - it holds almost twice as many prisoners as it should."
The deputy governor of Leicester Prison, Steve Clarke, said staff were doing their best to lessen the impact of overcrowding on inmates.
"We have excellent relationships between staff and prisoners so we have fewer problems than you might expect."