Cuba has been partying since Tuesday, with concerts, ballet performances and art exhibitions organized on behalf of the man who led the island nation for nearly 50 years before ill health led him to cede power to Raul in 2006.
The celebrations are to culminate late yesterday into today with a "Song of Loyalty" gala dedicated to the former leader at the Karl Marx Theater, Cuba's largest with a capacity of 5,000.
Most of the events have been organised by the Guayasamin Foundation, named for the Ecuadoran painter Oswaldo Guayasamin, a close friend of Castro. The organization is often involved in planning Castro's birthday celebrations.
It was, however, still unclear whether the guest of honor would make a public appearance.
"The commander-in-chief has not confirmed his participation in these events with us," said Pablo Guayasamin, son of the painter and a foundation member.
Castro's public appearances are increasingly rare. The last came in April, at the ruling Communist Party's annual congress, when Raul officially succeeded his older brother as party leader.
Since that time, Fidel has only been seen in video footage visiting ailing Venezuelan President Hugo Chavez -- who is receiving chemotherapy treatment in Cuba.