A patient, productive hitter throughout his career, Olerud won the American League batting title in 1993 and was runner-up for the National League batting title in 1998. Also a three-time Gold Glove winner, he was an excellent defensive first baseman and part of Sports Illustrated's "Greatest Infield Ever?" cover in 1999 with Edgardo Alfonzo, Rey Ordóñez, and Robin Ventura, when he played for the Mets.
Olerud was born to Lynda and John E. Olerud, a physician, dermatologist, and baseball player from Lisbon, North Dakota. The elder Olerud played college baseball for the Washington State Cougars as a catcher, and was the captain of the team which advanced to the semifinals of the College World Series in 1965. He was selected by the California Angels in the 1965 amateur draft and spent the next seven years studying medicine and playing minor league baseball.
At Interlake High School in Bellevue, Washington, east of Seattle, Olerud played varsity golf and baseball for three years. As a senior in 1986, he led the Saints to a state high school baseball championship as both a pitcher and first baseman.
As a true freshman in 1987, he hit .414 with 5 HR and 20 RBIs. As a pitcher, he went 8-2 with a 3.00 ERA and was an All-American. Washington State finished third in the six-team West I regional of the NCAA tournament.
In 1988, Olerud hit .464 with 23 HR, 81 RBIs, 108 hits, 204 total bases, and a .876 slugging percentage. As a pitcher, he had an undefeated 15–0 season, and threw 113 strikeouts with a 2.49 ERA. He was a consensus All-American as both a first baseman and pitcher and was named the Baseball America College Player of the Year. WSU again finished third in the six-team West I regional of the NCAA tournament.
Prior to his junior season in 1989, Olerud was running indoors on campus on January 11 when he collapsed; hospitalized in Pullman, he was airlifted to Spokane later in the day, accompanied by his father. It was diagnosed as a subarachnoid hemorrhage, which caused bleeding into the spinal column. He remained in the hospital for about two weeks after the seizure and lost fifteen pounds (7 kg), but was back in class by the end of January. A few weeks later in Seattle, further examinations revealed a brain aneurysm, and he underwent surgery in late February.