The leader of the 1959 Cuban Revolution, and the man who has outlasted nine hostile U.S. presidents, Castro said in his address to the nation that he could not consent to be elected president of the National Assembly and commander-in-chief of the armed forces due to health problems.
"It would betray my conscience to take up a responsibility that demands mobility and a total devotion that I am not in a physical condition to offer," his statement read.
"I am not bidding farewell to you. I want to fight on as a soldier of ideas...My voice will be heard," he went on.
The National Assembly is now expected to elect Castro's 76-year-old brother Raul as his successor. There has also been speculation that vice-president, Carlos Large, 56, could become Cuba's new leader.
Castro underwent stomach surgery in July 2006, handing over 'temporary' power to Raul Castro. His appearances have been far and few between since.
In December 2007, Castro announced he would not "cling to power" and stand in the way of a new generation of leaders. The announcement raised speculation that Castro's days as Cuban leader could be numbered.
As one of the few surviving iconic figures of the 20th century, Castro's departure as an active political figure opposed to 'U.S. imperialism' leaves a gap that only perhaps Hugo Chavez, the controversial and charismatic leader of Venezuela, will be able to fill.
