By Peg McEntee

SALT LAKE CITY (Reuters) - Utah's Brigham Young University, the Mormon Church's flagship education institution, has for the first time issued guidelines on when students may grow beards without violating its rule that men must be clean-shaven.

Under the private school's honor code, which forbids premarital sex, tattoos and drinking alcohol, and requires that men and women dress modestly, only certain students will be permitted to grow facial hair.

Exceptions will include medical conditions, theatrical production requests from The Church of Jesus Christ of Latter-day Saints media and drama departments, as well as religious observance and practice, according to the new standards published on Wednesday by the university in Provo, 50 miles (80 km) south of Salt Lake City.

BYU spokeswoman Carri Jenkins said religious cases, including for example beards worn by Sikh and Muslim students, will be worked out in coordination with the school's chaplain. Students with skin conditions that prevent shaving must get a note from the campus doctor.

The founder of Mormonism, Joseph Smith, was clean-shaven, and while Jenkins said it was unknown exactly when BYU put in place its ban on facial hair, its president during the 1960s had encouraged all male students to be clean-shaven.

"By the early '70s, it had become part of the Dress and Grooming Standards," she wrote in an email.

Other standards for men and women include "a clean and well-cared-for appearance," as well as a ban on body piercing, although a single earring in each ear is approved for women.

Last fall, some students wore cardboard beards as they held a demonstration to protest against the facial hair regulation.

(Reporting by Peg McEntee; Editing by Daniel Wallis and Eric Walsh)