1999–2000 Washington State Cougars men's basketball team

The 1999–2000 Washington State Cougars men's basketball team represented Washington State University for the 1999–2000 NCAA Division I men's basketball season. Led by first-year head coach Paul Graham, the Cougars were members of the Pacific-10 Conference and played their home games on campus at Beasley Coliseum in Pullman, Washington.

The Cougars were 6–22 overall in the regular season and 1–17 in conference play, last in the standings. There was no conference tournament this season; last played in 1990, it resumed in 2002.

Graham was hired in March 1999; he was previously an assistant at Oklahoma State under Eddie Sutton.