The appointed head of the Latter-day Saints says followers of the religion should no longer be referred to as Mormons.
Church leader Russell Nelson says people, whether in the church or not, should be calling it "the Church of Jesus Christ of Latter-day Saints".
The 93-year-old said God had impressed upon him the importance of the official name.
The Utah-based church has updated its online guide, saying the phrases "Mormon Church", "Mormon", and "Mormonism" should no longer be used.
The guidelines also stipulate the church's name should not be abbreviated to "LDS".
However, Mr Nelson said the church's central text will still be called the Book of Mormon.
Members of the Church of Jesus Christ of Latter-day Saints worship Jesus Christ, but have a series of radically different beliefs to those in Catholic, Protestant, and Orthodox denominations.
The religion was founded by Joseph Smith in the United States in the 19th Century, and has more than 12 million members around the world.