Love Letters of a Portuguese Nun (German: Die Liebesbriefe einer portugesischen Nonne) is a 1977 West German-Swiss film directed by Jesús Franco and produced by Erwin Dietrich, loosely based on the Letters of a Portuguese Nun attributed to Mariana Alcoforado. It starred Susan Hemingway, (German actress, born in 1960), and William Berger. Franco co-wrote the screenplay with producer Dietrich.

It tells the story of Maria, a girl in Inquisition-era Portugal, whom a priest sees cavorting with a boy. He orders her to become a nun as penance. In the convent Maria gets subjected to all sorts of torture and humiliation at the hands of the priest and the mother superior.

The movie is part of a genre known as "nunsploitation".