1986–87 Washington State Cougars men's basketball team

The 1986–87 Washington State Cougars men's basketball team represented Washington State University for the 1986–87 NCAA Division I men's basketball season. Led by fourth-year head coach Len Stevens, 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 10–17 overall in the regular season and 6–12 in conference play, tied for eighth in the standings.

The conference tournament debuted this year; seeded ninth, WSU lost to eighth-seed Arizona State by sixteen points in the opening round.

A month after the season ended, Stevens resigned in early April to become head coach at Nevada, then a member of the Big Sky Conference;  assistant Kelvin Sampson was soon promoted to head coach,  and led the program for seven seasons.

Postseason result
!colspan=5 style=| Pacific-10 Tournament