The 2004 United States Open Championship was the 104th U.S. Open, held June 17–20 at Shinnecock Hills Golf Club in Shinnecock Hills, New York. Retief Goosen won his second U.S. Open title, two strokes ahead of runner-up Phil Mickelson, the reigning Masters champion. The purse was $6.25 million with a winner's share of $1.125 million.

Late on Sunday in dry and breezy conditions, Goosen birdied the 16th hole and Mickelson double-bogeyed the par-3 17th. Goosen's previous U.S. Open win was in 2001 in a playoff at Southern Hills.

This was the fourth U.S. Open hosted by Shinnecock Hills. The former champions were James Foulis (1896), Raymond Floyd (1986), and Corey Pavin (1995). The second U.S. Open was held at Shinnecock in 1896, but ninety years went by before it hosted again. The 1986 edition was held on a completely revamped course. Floyd, age 43, entered the final round three shots behind and shot a 66 in difficult scoring conditions to win his fourth major.

The conditions were similar in 1995, with no one under par. Pavin played the final ten holes in three-under-par on the way to a 68 and the win. He hit a memorable 4-wood to the 72nd green to within 5 feet (1.5 m) and finished at even par 280.

Lengths of the course for previous major championships:

Ernie Els (4,8,9,10,11,13,16), Jim Furyk (8,9,16), Retief Goosen (9,10,16), Lee Janzen, Corey Pavin, Tiger Woods (3,4,5,9,11,12,16)

Nick Flanagan (a), Casey Wittenberg (a)

Phil Mickelson (11,16), Vijay Singh (9,11,12,16), Mike Weir (8,9,16)