"We are electing a new parliament at a complicated time when we have to face different situations and big decisions, bit by bit," Raul said.
"He is in good health. I know he has been writing a lot, up to four essays simultaneously.
Considering that he is 81, Fidel is strong, healthy and an intellectual powerhouse," he said.
Fidel, who has led Cuba since a 1959 revolution that created a communist state only 135km from the United States, hinted in December that he would not cling to power or stand in the way of a new generation.
The Cuban leader had to hand over the running of the country to his brother after emergency stomach surgery for an undisclosed illness in July 2006.
Since then he has only been seen in video clips and photographs.
Last week Castro wrote in a column that he was not physically able to speak in public for his re-election as a deputy and was sticking to writing instead.
Fidel cast his ballot in an envelope sent from his convalescence quarters.
|Fidel's influence still loom |
large over Cuba[EPA]
Some foreign observers believe Raul needs to be fully empowered to undertake sweeping economic reforms he has promised to improve the lot of Cubans.
However, Al Jazeera's Mariana Sanchez said Fidel's influence will loom large, because Cubans do not believe that much has changed since the temporary handover.
But some Cubans have said they do see a difference in how Raul is leading the country.
The acting president is encouraging Cubans to openly criticise shortcomings of how the government manages the country.
But what has not changed is the economic and political structure that has shaped the communist country for decades.
For weeks, authorities have urged the 8.4 million voters to go and vote to show support for Cuba's one-party system.