The 1980 IMSA GT Series season was the 10th season of the IMSA GT Championship auto racing series. It was a series for GTX class Group 5 cars and GTO and GTU class grand tourer cars. It began February 2, 1980, and ended November 30, 1980, after fourteen rounds.
Not all classes participated in shorter events. Races marked with All had all classes on track at the same time.
| Rnd | Race | Length | Class | Circuit | Date | |
|---|---|---|---|---|---|---|
| 1 | 24 Hour Pepsi Challenge | 24 Hours | All | Daytona International Speedway | February 2 February 3 | |
| 2 | Coca-Cola 12 Hours of Sebring | 12 Hours | All | Sebring International Raceway | March 22 | |
| 3 | Road Atlanta Grand Prix | 50 Miles (twice) | GTX/GTO | Road Atlanta | April 12 | |
| 45 Minutes | GTU | |||||
| 4 | Los Angeles Times/Toyota Grand Prix | 5 Hours | All | Riverside International Raceway | April 27 | |
| 5 | Datsun Monterey Triple Crown | 45 Minutes | GTU | Laguna Seca Raceway | May 4 | |
| 100 Miles | GTX/GTO | |||||
| 6 | Coca-Cola 400 | 45 Minutes | GTU | Lime Rock Park | May 26 | |
| 1 Hour 30 Minutes | GTX/GTO | |||||
| 7 | Pepsi Grand Prix | 100 Miles | GTO/GTU | Brainerd International Raceway | June 15 | |
| 8 | Paul Revere 250 | 250 Miles | All | Daytona International Speedway | July 4 | |
| 9 | Datsun's Golden State Challenge | 100 Miles | GTX/GTO | Golden State International Raceway | July 27 | |
| 75 Miles | GTU | |||||
| 10 | G.I. Joe's Grand Prix | 100 Miles | GTX/GTO | Portland International Raceway | August 3 | |
| 45 Minutes | GTU | |||||
| 11 | Molson Canadian 1000 | 6 Hours | All | Mosport Park | August 17 | |
| 12 | Pabst 500 | 500 Miles | All | Road America | August 31 | |
| 13 | Grand Prix of Road Atlanta | 45 Minutes | GTU | Road Atlanta | September 21 | |
| 50 Miles (twice) | GTX/GTO | |||||
| 14 | Championship Finale Daytona GT 250 | 250 Miles | All | Daytona International Speedway | November 30 |
| Rnd | Circuit | GTX Winning Team | GTO Winning Team | GTU Winning Team | Results |
|---|---|---|---|---|---|
| GTX Winning Drivers | GTO Winning Drivers | GTU Winning Drivers | |||
| 1 | Daytona |  #2 LM Joest Racing |  #54 Montura Racing | #62 Koll Motor Sports | Results |
| Reinhold Joest Rolf Stommelen Volkert Merl | Tony Garcia Alberto Vadia Terry Herman | Bill Koll Jim Cook Greg LaCava | |||
| 2 | Sebring | #6 Dick Barbour Racing | #44 Group 44 | #77 Mandeville Racing | Results |
Dick Barbour John Fitzpatrick | Bob Tullius Bill Adam | Roger Mandeville Jim Downing Brad Frisselle | |||
| 3 | Road Atlanta | #95 Whittington Bros. Racing | #99 Full-Time Racing | #7 Racing Beat | Results |
| Bill Whittington | Phil Currin | Walt Bohren | |||
| 4 | Riverside | #6 Dick Barbour Racing | #54 Montura Racing | #47 Brad Frisselle Racing | Results |
| Dick Barbour John Fitzpatrick | Tony Garcia Terry Herman | Brad Frisselle Yoshimi Katayama | |||
| 5 | Laguna Seca | #6 Dick Barbour Racing | #54 Montura Racing | #7 Racing Beat | Results |
| John Fitzpatrick | Tony Garcia | Walt Bohren | |||
| 6 | Lime Rock | #09 Preston Henn |  #63 Mendez Racing | #83 Electramotive | Results |
| John Paul Sr. John Paul Jr. | Luis Mendez | Don Devendorf | |||
| 7 | Brainerd | Did not participate | #63 Mendex Racing | #17 Racing Beat | Results |
| Luis Mendez | Jeff Kline | ||||
| 8 | Daytona | #6 Dick Barbour Racing | #44 Group 44 | #7 Racing Beat | Results |
| John Fitzpatrick | Bob Tullius | Walt Bohren | |||
| 9 | Golden State | #6 Dick Barbour Racing | #68 Mendez Racing | #7 Racing Beat | Results |
| John Fitzpatrick | Luis Mendez | Walt Bohren | |||
| 10 | Portland | #6 Dick Barbour Racing | #68 Mendez Racing | #7 Racing Beat | Results |
| John Fitzpatrick | Luis Mendez | Walt Bohren | |||
| 11 | Mosport | #6 Dick Barbour Racing | #44 JRT Quaker State | #17 Racing Beat | Results |
| John Fitzpatrick Brian Redman | Bob Tullius Bill Adam | John Morton Jeff Kline Walt Bohren | |||
| 12 | Road America | #18 JLP Racing | #44 Group 44 | #83 Electramotive | Results |
| John Paul Sr. John Paul Jr. | Bob Tullius Bill Adam | Don Devendorf Tony Adamowicz | |||
| 13 | Road Atlanta |  #30 MOMO/Electrodyne |  #46 DeNarvaez Enterprises | #7 Racing Beat | Results |
| Gianpiero Moretti | Terry Herman | Jeff Kline | |||
| 14 | Daytona | #30 MOMO/Electrodyne | #4 Group 44 | #32 Alderman Racing | Results |
| Gianpiero Moretti Reinhold Joest | Bill Adam | George Alderman |