Official website Cubadebate says Fidel Castro Diaz-Balart took his life Thursday after months of treatment for a "deeply depressed state." He was 68.
The eldest son of Cuba's former leader was known for his distinctive beard and resemblance to his father.
A brief note read on state television said that his treatment had "required a hospitalization regime then outpatient follow-up."
Castro Diaz-Balart's mother was Mirta Diaz-Balart, a woman from Cuba's aristocracy who Castro married in his youth before beginning the revolutionary struggle that later brought him and his brother Raul to power.