As a young university medical student in León in the 1970s, Téllez was recruited by the Sandinista National Liberation Front (FSLN).

[1][2] Téllez went on to become a comandante and fought alongside later president Daniel Ortega in the revolution that ousted dictator Anastasio Somoza Debayle in 1979.

She ultimately became a critic of repression and corruption under President Ortega and left the FSLN in 1995 to found the party Sandinista Renovation Movement (MRS), later renamed Unamos.

There was a subsequent release of key Sandinista political prisoners and a million-dollar ransom payment, which Téllez played a role in negotiating.

For five months she led Sandinista platoons throughout the country in skirmishes with the Nicaraguan National Guard: first in the Southern Front with Edén Pastora's forces, and later in Central and northern Nicaragua.

According to Sandinista Commander Mónica Baltodano, her raids on the northern provinces in conjunction with Cmdr Leticia Herrera columns surprised the enemy constantly and succeeded in dispersing their forces to take advantage.

[10] In 1994 she was elected to the national directorate of the SNLF as part of a movement to increase women's representation at the highest levels of the SNLF; other women elected at the same time included Dorotea Wilson, Mónica Baltodano, Benigna Mendiola and Myrna Cunningham.

Téllez suspended her hunger strike on June 16, after doctors told her she would suffer irreparable damage if she continued her fast.

Her book, "Muera la Gobierna: colonizacion en Matagalpa y Jinotega 1820-1890" documents the process of internal colonization and land dispossession carried out by the Nicaraguan state in the northern region of Nicaragua between 1820 and 1890.

In 2004 she was appointed Robert F. Kennedy Visiting Professor in Latin American studies at the Harvard Divinity School, but was barred from obtaining an entry visa to the United States under the Patriot Act, on grounds that she was a terrorist, citing as evidence the raid on the Nicaraguan National Palace in Managua.

[24][25] This prompted 122 members of the academic community from Harvard and 15 other North American universities to publish a statement in her defense, stating: The accusation made by the State Department against Dora María Téllez... amounts to political persecution of those who have engaged in overthrowing the atrocious dictatorship of Anastasio Somoza in Nicaragua...This regime was almost universally viewed as criminal and inhumane, and yet it was financially and militarily supported by the United States...In reference to dictatorships, just as the State Department cannot affirm that the activities of Nelson Mandela against the atrocious dictatorship of apartheid in South Africa were terrorist activities, neither can it affirm that Dora María's activities against the atrocious Somoza dictatorship were terrorist.