She was also an assistant of Hispano-American Literature at the University of the Republic's Faculty of Humanities and Sciences, a position from which she was dismissed by the dictatorship.
Rein was one of the members of the jury, along with Juan Carlos Onetti and Jorge Ruffinelli, of the weekly's fateful short story contest, for which Onetti, she, and the author of the story "El guardaespaldas", Nelson Marra [es], were imprisoned in 1974.
Her play El herrero y la muerte, written with Jorge Curi, was on the bill for more than six years at the Teatro Circular [es].
Juana de Asbaje (1993) won her the Florencio Award [es] for the best play of the year.
[4] Mercedes Rein was a contributor to the weekly Brecha and a member of the Academia Nacional de Letras.