The 1990 du Maurier Classic was contested from June 28 to July 1 at Westmount Golf & Country Club. It was the 18th edition of the du Maurier Classic, and the 12th edition as a major championship on the LPGA Tour.
This event was won by Cathy Johnston-Forbes.
Final leaderboard
edit| Place | Player | Score | To par | Money (US$) |
|---|---|---|---|---|
| 1 |  Cathy Johnston-Forbes |
65-70-70-71=276 | −16 | 90,000 |
| 2 | Patty Sheehan |
69-70-70-69=278 | −14 | 55,500 |
| 3 | Beth Daniel |
74-66-71-70=281 | −11 | 40,500 |
| 4 |  Liselotte Neumann |
68-72-70-72=282 | −10 | 31,500 |
| 5 | Missie Berteotti |
74-68-69-72=283 | −9 | 25,500 |
| T6 | Jody Anschutz |
70-72-70-72=284 | −8 | 19,350 |
| Gina Hull |
70-68-76-70=284 | |||
| T8 | Pat Bradley |
73-69-70-73=285 | −7 | 14,850 |
| Patti Rizzo |
67-69-73-76=285 | |||
| T10 | Jane Geddes |
72-67-74-73=286 | −6 | 12,000 |
| Betsy King |
70-72-70-74=286 |