The 1989 winner of the Cervantes Prize (the top Spanish literature award), Roa Bastos died on Tuesday despite undergoing extensive surgery last week.
He was first treated for his heart condition in Cuba in 2003.
Cuban President Fidel Castro visited Roa Bastos' home on his last visit to Paraguay, a sign of the reverence the writer enjoyed across the Americas.
His most famous work - I, the Supreme - was published in 1974, and is considered a masterpiece of contemporary Spanish-language literature. It tells the story of Jose Gaspar Rodriguez Francia, a self-declared perpetual dictator of Paraguay in the 19th century.
Since his childhood, he said he felt the need to oppose power, which he called "a tremendous stigma, a kind of human egoism that seeks to control the personalities of others".
The writer went into exile in 1947 after suffering persecution at the hands of a military tyranny. He spent a half-century living outside the landlocked South American nation ruled by brutal ruler Alfredo Stroessner from 1954 to 1989.
Roa Bastos settled in neighbouring Argentina, where he worked at several jobs, including mailman, while continuing to write. He became a prominent member of the Buenos Aires literary circle, alongside Argentine greats, Jorge Luis Borges and Ernesto Sabato.
In 1960, he had his first major literary success with Son of Man, a saga on the painful history of Paraguay.
In 1976, he moved to Toulouse, France, where he taught at the university, and later went to Spain. He returned to Paraguay to live in 1996.
Roa Bastos was one of the few well-known Latin American writers who did not break with Communist Cuba after a 2003 crackdown on dissent. His work has been translated into 25 languages.