Some local media have been saying this week that Chavez, 56, may be suffering from a cancer in the nasal cavity.
His failure to appear on Wednesday's first day of campaigning for the September 26 parliamentary elections fuelled the speculation, although it later transpired Chavez was holding a lengthy meeting with his mentor, Fidel Castro, in Cuba.
The squalid ones want to kill me, Chavez said after returning to Caracas for a graduation ceremony of socialist medicine students. Now they're inventing that I have cancer, that I'm dying. That's what they want, he added laughing.
Former soldier Chavez, who has inherited Castro's mantle as Latin America's leading critic of the United States, took power in 1999 and plans to run again for the presidency in 2012.
Although not in the same shape he was as a sportsman in his youth, Chavez still likes to demonstrate his physical vigour with marathon speeches or games of baseball.
The spectre of cancer is a delicate subject in South American political circles at the moment, given that Paraguayan President Fernando Lugo was diagnosed with the disease this month.
Brazil's front-running presidential candidate, Dilma Rousseff, had a tumour removed last year and underwent therapy for lymphoma cancer, but now has a clean bill of health.
CASTRO 'DEVILISHLY' WELL
Chavez said he spent a happy five hours in Havana discussing global politics with Castro, 84, who has reappeared on the public stage in recent weeks after ill health led him to hand over the Cuban presidency in 2008.
He's devilishly well, I tell you, (showing) vitality, energy, Chavez said.
He's taken on a sort of crusade against war, he said of Castro's exhortations to U.S. President Barack Obama to avert a nuclear war over Iran.
Fidel is saying, 'Be careful,' because the imperialists in their madness could lead us to nuclear war, God spare us.
(Reporting by Eyanir Chinea; Writing by Andrew Cawthorne; Editing by Peter Cooney)