Early in 1968 when the Tet Offensive broke out, Hoa and her husband, a mathematician, fled Saigon to a Vietcong hideout in the jungle. There, the couple's son died of encephalitis. Although she never recovered from the personal loss, she put on a brave face in an interview with American journalist Stanley Karnow, quipping that her son was "only one among millions". She was appointed as the Vietcong's deputy minister of health in its Provisional Revolutionary Government, a body that was set up at the order of North Vietnam to give the Vietcong political legitimacy. She was named as a "heroine of the revolution. Of her involvement with the Vietcong, she said in 1981, "We had no choice. We had to get rid of the foreigners."
Critic of communism
Following the war she administered a children's hospital in the newly renamed Ho Chi Minh City. After the communist takeover, Hoa eventually became a vocal critic of communist rule. She stated "I have been a communist all my life, but now I've seen the realities of Communism, and it is a failure — mismanagement, corruption, privilege, repression. My ideals are gone." Hoa also attacked the cadres who later moved into the south after the reunification and dominated the communist ruling class, who she felt were inattentive to southern regional characteristics and sensitivities. She was particularly critical of the forced land collectivisation programs, noting that some southern peasants went to the Vietcong due to their policy of land reform, whereas the South Vietnam had been proponents of land policies that were favourable to the landed gentry. Of the northerners who ruled over the south, she expressed her contempt, saying that "They behave as though they conquered us." At the time, the failure of the rice harvest and declining food rations had seen record levels of malnutrition at the hospital that she ran. In 1990, she declared to Karnow that "Communism has been catastrophic. Party officials have never understood the need for rational development. They've been hypnotized by Marxist slogans that have lost validity — if they were ever valid. They are outrageous." Talking of the corruption practiced by the communist officials and their wives, she said that it was equivalent to what occurred in South Vietnam:"This is very much a feudal society, whatever its ideological veneer."