[6] He then did his medical residency and earned a Ph.D. at the University of Minnesota, where he was a member of the research team developing the heart-lung machine that in 1951 supported the first human open-heart surgery using cardiopulmonary bypass.

After serving in the U.S. Army Medical Corps during the Korean War, Nelson returned to Salt Lake City and accepted a professorship at the University of Utah School of Medicine.

[11][12] His parents were not active in the Latter-day Saint faith while he was a youth, but they did send him to Sunday School,[13] and he was baptized a member of the LDS Church at age 16.

[14] Nelson studied at LDS Business College in his mid-teens (concurrently with high school enrollment) and worked as an assistant secretary at a bank.

[15] He graduated from high school at age 16 and enrolled at the University of Utah,[16][17] where he was a member of the Beta Epsilon chapter of Sigma Chi and Owl and Key.

He became a member of surgeon Clarence Dennis's research team developing the heart-lung machine that in April 1951 supported the first human open-heart surgery using cardiopulmonary bypass.

While on duty, he was assigned to a research group formed by the commandant of the graduate school at Walter Reed, Col. William S. Stone and led by Fiorindo A. Simeone, a professor of surgery at Case Western Reserve University in Cleveland who had been a clinical investigator in the Mediterranean Theater during World War II.

There he built his own heart-lung bypass machine and employed it to support the first open-heart surgery in the United States west of the Mississippi River.

[26] In March 1956, he performed the first successful pediatric cardiac operation at the SLGH, a total repair of tetralogy of Fallot in a four-year-old girl.

[25] In an indication of his surgical skill, a 1968 case series of his aortic valve replacements demonstrated an exceptionally low peri-operative mortality.

[29] Later, he performed the same operation on future LDS Church president Spencer W. Kimball, replacing his damaged aortic valve.

[33] In 1981, Nelson held appointments as a visiting professor of surgery at the National Institute of Cardiology in Mexico City and the Catholic University in Santiago, Chile.

[33] Nelson traveled extensively as a medical doctor and addressed conferences in many parts of Latin America and Africa, as well as in India and China.

[25] In 2015, the University of Utah, along with the American College of Cardiology, created the Russell M. Nelson MD, PhD Visiting Professorship in Cardiothoracic Surgery.

In Washington DC, he was a counselor in the bishopric of the ward that Ezra Taft Benson (then an apostle) regularly attended while serving as Secretary of Agriculture to Dwight D. Eisenhower.

[38] After returning to Salt Lake City, he was called as priest quorum advisor in the Garden Park Ward, working with over 50 boys ages 16 to 18.

The call to serve in this position had been extended to Nelson by Richard L. Evans, an apostle and the lead figure over publicity efforts on Temple Square.

There was also a shift from having members of the Sunday School general board do all the training for new teachers to providing materials which developed into the book Teaching: No Greater Call.

[57][58] Citing "continuing revelation" and a changing global context, this policy was adjusted in 2019, such that First Presidency approval was no longer required for the children to be baptized.

He pronounced blessings upon Croatia, Slovenia, Macedonia, Bosnia and Herzegovina, and Kosovo while visiting each of those countries; these serve as addendums to Monson's 1985 dedication of Yugoslavia for the preaching of the gospel.

[68] In 1995, Nelson went to Beijing, along with Neal A. Maxwell and other LDS Church leaders, on an official invitation of Li Lanqing, the Vice Premier of China.

[76] The first trip, called a global ministry tour by the church, occurred in April 2018, when Nelson along with his wife, and Jeffrey R. Holland and his wife, met with Latter-day Saints in London, England; Jerusalem; Nairobi, Kenya; Harare, Zimbabwe; Bengaluru, India; Bangkok, Thailand; Hong Kong; and Laie, Hawaii.

[77] In June 2018, Nelson traveled to Alberta, Canada, where his second wife was born and raised, and gave three devotional addresses in three consecutive evenings.

Nelson began his presidency two days after his ordination with a short broadcast to church members in January 2018 before then holding a press conference.

This broadcast ahead of the press conference was unprecedented and provided the new leaders an opportunity to briefly address the entire church immediately.

[89] During the church's April general conference, Nelson appointed Asian-American Gerrit W. Gong and Brazilian Ulisses Soares to the Quorum of the Twelve Apostles, both of whom had been serving in the Presidency of the Seventy.

[91] June 2018 began with a First Presidency-sponsored celebration of the 40th anniversary of the revelation extending priesthood and temple blessings to all worthy members without regard to race, in which Nelson gave concluding remarks.

"[97][98][99] In the October 2018 general conference, Nelson shortened the length of Sunday church meetings to 2 hours, from the previous standard of 3.

During his April 2018 visit to India, Nelson stated to church members that the Lord had instructed him to announce the temple the night before general conference, though he had not originally planned to do so.

Days later, the Shanghai Municipal Ethnic and Religious Affairs Bureau responded saying it "knew nothing about the American Mormon Church .