Uganda's Supreme Court has refused an appeal by more than 400 death row inmates to abolish the death penalty, reported BBC.
But the judges ruled it was unreasonable to keep convicts on death row for more than three years.
It means most of the prisoners who brought the case, arguing that hanging was cruel and inhumane, will have their sentences commuted to life in prison.
Although the death penalty has not been used since 1999, the court said it acted as a deterrent to murder.
The BBC's Joshua Mmali in the capital, Kampala, says four prisoners were in court for the ruling.
But he says they did not understand the implications of the judges' ruling until their lawyer explained it to them.
The appeal by the prisoners on death row was supported by Ugandan human rights groups.