1990 Seattle Mariners season

Offseason

• November 13, 1989: Jeff Schaefer was signed as a free agent by the Mariners.
• December 7, 1989: Pete O'Brien was signed as free agent by the Mariners.

  Regular season

• June 2: Randy Johnson threw a no-hitter versus the Detroit Tigers, the first for the franchise. He was also the tallest pitcher in Major League history to throw a no-hitter. It was the 2101st game in Mariners history, played on a Saturday night in the Kingdome.
• September 14: Ken Griffey Sr. and Ken Griffey, Jr. hit back-to-back home runs in the top of the first inning against the California Angels. Through , it remains the only occurrence of consecutive homers by a father and son in MLB history.

  Opening Day starters

• Scott Bankhead
• Greg Briley
• Darnell Coles
• Alvin Davis
• Brian Giles
• Ken Griffey, Jr.
• Jeffrey Leonard
• Pete O'Brien
• Harold Reynolds
• Dave Valle

  Season standings

Record vs. opponents

Notable transactions

• June 4: 1990 Major League Baseball Draft
• *Marc Newfield was selected by the Mariners in the first round, and he signed on June 10.
• *Bret Boone was selected by the M's in the fifth round, and he signed on June 8.
• June 18: Darnell Coles was traded by the Mariners to the Detroit Tigers for Tracy Jones.
• June 19: Mario Díaz was traded by the Seattle Mariners to the New York Mets for Brian Givens.
• August 29: Ken Griffey, Sr. was signed as a free agent by the Mariners.
• September 18: Rick Rentería was released by the Mariners.

  Roster

The Griffeys

• Ken Griffey, Sr. joined his son to become the first father and son to play in a game together. The game was played in the Kingdome against the Kansas City Royals on August 31. The Griffeys became the first father-and-son teammates; he also hit back-to-back home runs with his son on September 14.

  Line Score

Batting

Pitching

Player stats

Batting

Starters by position

Other batters

Pitching

Starting pitchers

Other pitchers

Relief pitchers

Farm system