UN humanitarian coordinator Manuel da Silva on Tuesday said a joint survey with the government conducted between mid-May and mid-June showed rates had fallen to about 0.8/10,000 deaths a day, below the "crisis threshold" of 1/10,000.
"This rate is three times lower than the rate registered in the previous survey," da Silva said.
But he warned that despite an improvement in the figures, "the health of the people remains extremely fragile".
"While in North Darfur injury was an important cause, accounting for nearly a third of deaths, diarrhoea remains the major cause of death all over the region," he said.
"Nearly 50% of the children died of this disease, which is preventable."
Da Silva said improving sanitation and access to clean water would reduce the number of deaths occurring as a result of preventable diseases and also called for measures to fight malaria.
Fighting has raged in Darfur since February 2003, when local groups launched a rebellion in the name of the region's black African tribes against marginalisation by the Khartoum government.
Since the war began, 180,000 to 300,000 people are thought to have died, many of them from famine and disease, and 2.4 million have been displaced from their homes.