There were 78 suicides in prisons in England and Wales 2005, down 18% on the previous year's figure of 95, the government has said.
Four of those who died were women
A further 131 inmates were resuscitated following self-harm incidents during 2005, its figures showed.
Of those who died last year, four were female. Thirteen women inmates took their own lives in 2004.
The prison population hit an all-time high in 2005, with 77,800 inmates - 373 short of the total capacity.
Baroness Scotland, minister for criminal justice and offender management, said: "Every death in custody is a terrible tragedy for the families left behind and also has a profound effect on staff and other prisoners.
"The Government takes the issue of suicide in prisons very seriously and, in the face of population pressures, suicide prevention efforts have continued with unprecedented energy and commitment.
"There has been a fall in the number of self-inflected deaths in prison last year, but we know we must never be complacent.
"The improvement is testament to the hard work of staff and the prisoner centred initiatives that have been introduced across the estate."
A prison service spokesman said despite this year's population pressures, suicide prevention efforts had continued.
In total, 41 prisons had implemented a new care plan system for at-risk prisoners, which would be extended to all prisons by mid 2007.