The Venezuelan president first announced he was battling cancer in June 2011.
Chavez has not disclosed what type of cancer he has, and the Venezuelan government has released few details about his illness, fueling widespread speculation about his health and political future.
Last year, Chavez had surgery to remove a cancerous tumor and he has undergone further surgery and radiation in Cuba since. He returned to the island nation this month for more surgery after publicly revealing that his cancer had returned.
He underwent a six-hour surgical procedure on December 11 that Maduro, in a televised address, declared a success.
A week after the president's surgery, Venezuelan Information Minister Ernesto Villegas said Chavez was battling a respiratory infection.
Recently Villegas and Maduro have struck a somber tone when discussing the president's illness, in contrast to previous government messages about his health. Villegas has suggested Chavez might not be not be back in Venezuela in time for his inauguration, which is scheduled for January 10.
Chavez addressed the delicate nature of his health before leaving Venezuela for Cuba. He said that if his condition were to worsen, Maduro should replace him as president. It was the first time Chavez had spoken about a possible successor.