He is best known for his complex novel Yo el Supremo (I the Supreme) and for winning the Premio Miguel de Cervantes in 1989, Spanish literature's most prestigious prize.

[1] It was here, some 200 kilometres (120 mi) to the south of the Paraguayan capital of Asunción, that Roa Bastos learned to speak both Spanish and Guaraní, the language of Paraguay's indigenous people.

[2] His uncle's extensive personal library provided the young Roa Bastos with his first exposure to the classical Spanish literature of the Baroque and Renaissance traditions that he would imitate in his early poetry throughout the 1930s and 1940s.

[2] His experience of Guaraní social customs and language combined with the traditional Spanish education that he received in Asunción, created a cultural and linguistic duality that would manifest itself in much of Roa Bastos's writing.

[4] His rural upbringing also exposed Roa Bastos to the exploitation and oppression of the indigenous and peasant peoples of Paraguay,[1] which would become a prominent theme in his writing.

"[2] Instead of glory he found "maimed bodies" and "destruction" which left him to question "why two brother countries like Bolivia and Paraguay were massacring each other", and as a consequence Roa Bastos became a pacifist.

In the early 1940s he spent significant time on the yerba mate plantations in northern Paraguay, an experience he would later draw upon in his first published novel, Hijo de hombre (1960; Son of Man).

[6] In 1942 he published a book of poems in the classic Spanish style, which he titled El Ruiseñor De La Aurora (The Dawn Nightingale), a work he later renounced.

[8] During the 1947 Paraguayan Civil War, Roa Bastos was forced to flee to Buenos Aires, Argentina, because he had spoken out against President Higinio Moríñigo.

[6] In 1953 the collection of 17 short stories El trueno entre las hojas (1953; Thunder Among the Leaves) was published and circulated internationally, but it was not until the 1960 publication of the novel Hijo de hombre (Son of Man) that Roa Bastos won major critical and popular success.

Roa Bastos further established himself as a screenwriter with the screenplay of Shunko (1960), directed by Lautaro Murúa and based on the memoirs of a country school teacher.

In 1961 he once again collaborated with Murúa for Alias Gardelito (1961), which depicted the lives of urban petty criminals and became a major independent film of the nuevo cine movement.

When Jorge Rafael Videla's military dictatorship came to power in 1976, however, the book was banned in Argentina, and Roa Bastos was exiled once again, this time to Toulouse, France.

[4] Although he had been allowed to visit Paraguay to work with a new generation of Paraguayan writers, starting in 1970, he was again barred from entry in 1982, for purportedly engaging in subversive activities.

[4] Hijo de hombre (1960; Son of Man), Roa Bastos's first published and award-winning novel, represents his definitive break with poetry.

[15] It is seen as a refined "outgrowth" of his earlier works of short fiction such as El trueno entre las hojas (1953), which also dealt with themes of political oppression and social struggle in Paraguay.

[17] Like his later Yo, el Supremo, Hijo de hombre draws upon a series of Paraguayan legends and stories dating back to start of Dr. Francia's dictatorship in 1814.

[16] Hijo de hombre builds upon a system of Christian metaphors as part of the Neobaroque concept of Magic Realism, in order to examine the pain of being Paraguayan.

It has been suggested that it "[is] more immediately and unanimously acclaimed than any novel since One Hundred Years of Solitude, [and the] strictly historical importance [may] be even greater than that of García Márquez's fabulously successful creation.

[26] Barrett's essay "Lo que son los yerbales" is a severe critique of the exploitation of workers on yerba mate tea plantations.

Roa Bastos spent part of the early 1940s documenting this same issue and there is much speculation about the role of "Lo que son los yerbales" in the creation of his first major novel Hijo de hombre.

"[34] His work reveals an intense preoccupation not only with contemporary Paraguay but with its history, looking back to the beginning of the 19th century and the rule of Dr. Gaspar de Francia (whose life is the focus of Yo, el Supremo).

[35] While key historical figures and events interest Roa Bastos, it is the impact of these "socio-historical roots" on "the nature of the masses" that forms the central theme of his literary work.

[37] In El Fiscal (1993), a third novel about the abuses of political power—this time focusing on Stroessner's régime—Roa Bastos again offers an alternative to the accepted versions of events in Paraguay and challenges "the intelligibility of history".

[44] The preservation and widespread use of an indigenous language after centuries of European immigration is unique in Latin America, and Guarani remains a symbol of Paraguayan nationalism and an "important vehicle for interpreting the country's reality".

In his lifetime he made important contributions to Latin American Boom writing,[48] to the related Dictator Novel,[49] and to the Nuevo Cine film movement through screenplays like Alias Gardelito (1961).

[10] Roa Bastos's influence can be found in the works of many foreign post-boom writers, including Mempo Giardinelli, Isabel Allende, Eraclio Zepeda, Antonio Skármeta, Saul Ibargoyen, and Luisa Valenzuela.

[50] Roa Bastos's relationship with his country, unbroken by over 40 years of exile, was considered so important that in 1989 he was invited back by Paraguay's new president, Andrés Rodríguez, following the collapse of the Stroessner regime.

[13] Even before Yo, el Supremo, Roa Bastos was considered part of "the pantheon of great writers" by some critics, due to Hijo de hombre.

According to Juan Manuel Marcos, Yo, el Supremo "anticipates many of the post-boom writing techniques" such as "the carnivalization of historical discourse, transtextualization, and parody".