Continuing upon the success of the previous four seasons under Dennis Erickson, the Vandals were defending conference champions and finished the regular season at 8–3 and 5–2 in the Big Sky, tied for second. Led by senior quarterback Scott Linehan, Idaho qualified for the I-AA playoffs for the second straight season.
The Vandals defeated rivalBoise State for the fifth consecutive year, the fifth of twelve straight over the Broncos, but lost twice to nemesis Nevada-Reno, who were top-ranked in I-AA and undefeated in the regular season. Uncommon for a playoff team, the Vandals were shut out at home 24–0 by Northern Arizona in late October.
Division I-AA playoffs
The I-AA playoffs were expanded from 12 to 16 teams in 1986, eliminating the first round bye for the top four seeds. Idaho and Big Sky champion Nevada-Reno were the only two teams selected from the West, and were paired up in the first round in Reno two days after Thanksgiving. In mid-October the teams played a close defensive game, and the Vandals came up short by four points. The rematch in the post-season was not close as the Wolf Pack prevailed 27–7, improving their record over Idaho to 8–1 since joining the Big Sky in 1979.
The 1986 team included two future NFL head coaches: quarterback Scott Linehan and offensive lineman Tom Cable. Future NFL players with lengthy pro careers included guard Mark Schlereth (redshirt sophomore) and redshirt freshman John Friesz, a future collegiate hall of fame quarterback was Linehan's back-up in 1986. Friesz was a three-year starter (1987–89) and defeated Nevada-Reno all three seasons, including the first-ever victory in Reno in 1988.
Linebacker Tom Hennessey was a repeat selection to the all-conference team. Eight Vandals were included on the second team: safety Mark Tidd, linebacker Nolan Harper, defensive end Kord Smith, quarterback Scott Linehan, running back Steve Jackson, wide receiver Brant Bengen, and tackles Paul Taggert and Greg Hale.