At the age of eighteen, Sainz left home to work as a journalist in the magazine Visión.
This novel marked the beginning of the literary movement "la Onda", of which other Mexican writers, such as José Agustín and Parmenides García Saldaña, formed part.
In 1968, Sainz travelled to the University of Iowa to participate in the International Writing Program, where he started and completed his second novel, Obsesivos días circulares.
Upon his return to Mexico, he wrote La princesa del Palacio de Hierro,[4] which won the Xavier Villaurrutia Award in 1974.
It was translated into English by Andrew Hurley and published as The Princess of the Iron Palace by Grove Press in 1987.