Sudanese magnate Mo Ibrahim will not be awarding any African ex-leader his $5m (£3m) annual prize for good governance.
Mr Ibrahim gave no reason for the decision, saying he had always intended for there to be years when no prize would be awarded.
Now in its third year, the prize is given to a democratically elected leader from sub-Saharan Africa who has served their term and then left office.
South Africa's Thabo Mbeki and Ghana's John Kufuor had been the favourites.
The winners receive $5m over 10 years, and then $200,000 a year for life after that - the most valuable individual annual award in the world.
Mr Ibrahim said people could draw their own conclusions about why no prize was awarded this year.
But he said there was "no issue of disrespect" meant towards eligible candidates.
"The prize committee welcomed the progress made on governance in some African countries while noting with concern recent setbacks in other countries," said a statement from the panel which made the decision.
"This year the prize committee has considered some credible candidates. However, after in-depth review, the prize committee could not select a winner."
Former president of Ireland and UN High Commissioner for Human Rights Mary Robinson, one of the panel-members, said that if there had been a similar award for former European leaders this year, it might have been equally difficult to select a worthy winner.
BBC Africa analyst Martin Plaut says Mr Ibrahim established the prize because well-run African democracies are not thick on the ground.
Mr Ibrahim argues that the prize is needed because many African leaders come from poor backgrounds and are tempted to hang on to power for fear that poverty is what awaits them when they give up the levers of power.
But our analyst says recent evidence of the prize's effectiveness across Africa is not encouraging.
Uganda, Chad and Cameroon have all changed their constitutions so their leaders can retain their positions.
There have been coups in Guinea, Mauritania and Madagascar, as well as several elections that fell well short of international standards.
And the countries that have received most praise from Mo Ibrahim's foundation this year - Mauritius, Cape Verde and Seychelles - are far from the continent's centres of power.
Botswana's former President Festus Mogae won the prize last year, after two terms at the helm of one of Africa's least corrupt and most prosperous nations.
The inaugural prize was given to Joaquim Chissano, Mozambique's former president, who has since acted as a mediator in several African disputes.