The 1998 Monterey Sports Car Championships was the final race for the 1998 IMSA GT Championship season and the final race for the IMSA GT Championship before the series would be reorganized into the American Le Mans Series. It took place on October 25, 1998, at Laguna Seca Raceway. This event was a shared event with the FIA GT Championship (report here).
Class winners in bold.
| Pos | Class | No | Team | Drivers | Chassis | Tyre | Laps |
|---|---|---|---|---|---|---|---|
| Engine | |||||||
| 1 | WSC | 2 |  BMW Motorsport |  Didier de Radiguès  Bill Auberlen | Riley & Scott Mk III | M | 81 |
| BMW 4.0 L V8 | |||||||
| 2 | GT1 | 4 | Panoz Motorsports |  Andy Wallace  David Brabham | Panoz GTR-1 | M | 81 |
| Ford (Roush) 6.0 L V8 | |||||||
| 3 | GT1 | 5 | Panoz Motorsports | Johnny O'Connell  Éric Bernard | Panoz GTR-1 | M | 81 |
| Ford (Roush) 6.0 L V8 | |||||||
| 4 | WSC | 16 | Dyson Racing | James Weaver Butch Leitzinger | Riley & Scott Mk III | G | 81 |
| Ford 5.0 L V8 | |||||||
| 5 | GT2 | 72 | Konrad Motorsport |  Jan Lammers  Franz Konrad | Porsche 911 GT2 | D | 78 |
| Porsche 3.6 L Turbo Flat-6 | |||||||
| 6 | WSC | 7 | Doyle-Risi Racing | Eric van de Poele  Wayne Taylor | Ferrari 333 SP | P | 78 |
| Ferrari F310E 4.0 L V12 | |||||||
| 7 | WSC | 28 | Intersport Racing | Jon Field Rick Sutherland | Riley & Scott Mk III | G | 78 |
| Ford 5.0 L V8 | |||||||
| 8 | WSC | 27 | Doran Enterprises, Inc. | Didier Theys  Fredy Lienhard | Ferrari 333 SP | Y | 77 |
| Ferrari F310E 4.0 L V12 | |||||||
| 9 | GT2 | 71 | Marcos Racing International | Cor Euser Herman Buurman | Marcos LM600 | ? | 76 |
| Chevrolet 6.0 L V8 | |||||||
| 10 | GT3 | 23 | Alex Job Racing | David Murry Cort Wagner | Porsche 964 Carrera RSR | P | 77 |
| Porsche 3.8 L Flat-66 | |||||||
| 11 | GT2 | 56 | Martin Snow Racing | Martin Snow Melanie Snow | Porsche 911 GT2 | ? | 75 |
| Porsche 3.6 L Turbo Flat-6 | |||||||
| 12 | GT3 | 6 | Prototype Technology Group | Peter Cunningham Mark Simo | BMW M3 | Y | 75 |
| BMW 3.2 L I6 | |||||||
| 13 | WSC | 88 | Dollahite Racing | Mike Davies Bill Dollahite | Ferrari 333 SP | Y | 75 |
| Ferrari F310E 4.0 L V12 | |||||||
| 14 | GT3 | 68 | The Racer's Group | Vic Rice Kevin Buckler | Porsche 911 Carrera RSR | ? | 74 |
| Porsche 3.8 L Flat-6 | |||||||
| 15 | GT2 | 99 | Schumacher Racing | Larry Schumacher John O'Steen Andy Pilgrim | Porsche 911 GT2 | P | 73 |
| Porsche 3.6 L Flat-6 | |||||||
| 16 | GT3 | 55 | AASCO Performance | Tim Ralston Charles Slater | Porsche 911 Carrera RSR | ? | 73 |
| Porsche 3.8 L Flat-6 | |||||||
| 17 | GT3 | 1 | Prototype Technology Group | Bill Auberlen Peter Cunningham | BMW M3 | Y | 73 |
| BMW 3.2 L I6 | |||||||
| 18 | WSC | 63 | Downing Atlanta | Chris Ronson Jim Downing | Kudzu DLY | G | 72 |
| Mazda R26B 2.6 L 4-Rotor | |||||||
| 19 | WSC | 60 | Kopf Race Products | Kris Wilson Shane Donley | Keiler KII | G | 72 |
| Ford 5.0 L V8 | |||||||
| 20 | GT3 | 17 | AASCO Performance | Tom Peterson Dennis Aase | Porsche 911 Carrera RSR | ? | 71 |
| Porsche 3.8 L Flat-6 | |||||||
| 21 | GT3 | 22 | Alex Job Racing | Kelly Collins Darryl Havens | Porsche 911 Carrera RSR | ? | 67 |
| Porsche 3.8 L Flat-6 | |||||||
| 22 DNF | WSC | 20 | Dyson Racing | Dorsey Schroeder Elliot Forbes-Robinson | Riley & Scott Mk III | G | 65 |
| Ford 5.0 L V8 | |||||||
| 23 DNF | WSC | 51 | Fantasy Junction | Spencer Trenery Bruce Trenery | Cannibal | G | 61 |
| Chevrolet 6.0 L V8 | |||||||
| 24 DNF | WSC | 29 | Intersport Racing |  Jacek Mucha Ken Dromm | Riley & Scott Mk III | G | 57 |
| Ford 5.0 L V8 | |||||||
| 25 DNF | GT3 | 67 | The Racer's Group | Steve Pelke Scott Killips | Porsche 911 Carrera RSR | ? | 40 |
| Porsche 3.8 L Flat-6 | |||||||
| 26 DNF | GT3 | 76 | Team A.R.E. | Mike Doolin Scott Peeler | Porsche 993 Carrera RSR | Y | 31 |
| Porsche 3.8 L Flat-6 | |||||||
| 27 DNF | GT3 | 10 | Prototype Technology Group | Ross Bentley Mark Simo | BMW M3 | Y | 28 |
| BMW 3.2 L I6 | |||||||
| 28 DNF | WSC | 3 | BMW Motorsport | Steve Soper Hans-Joachim Stuck | Riley & Scott Mk III | M | 20 |
| BMW 4.0 L V8 | |||||||
| 29 DNF | WSC | 8 | Transatlantic Racing Services | Scott Schubot Henry Camferdam | Riley & Scott Mk III | D | 16 |
| Ford 5.0 L V8 | |||||||
| 30 DNF | GT2 | 25 | Alex Job Racing | 'Trip' Goolsby Don Kitch Michael Petersen | Porsche 964 Carrera RSR | ? | 11 |
| Porsche 3.8 L Flat-6 | |||||||
| 31 DNF | GT2 | 65 | Saleen Allen Speedlab | Terry Borcheller Andy Pilgrim Ron Johnson | Saleen Mustang SR | ? | 7 |
| Ford 5.9 L V8 |