The Kentucky Oaks is a Grade I stakes race for three-year-old Thoroughbred fillies staged annually in Louisville, Kentucky, United States. The race currently covers 1⅛ miles (1811 metres) at Churchill Downs; carry 121 pounds (55 kg).

The Kentucky Oaks dates back to the earliest days of Churchill Downs, which was known as the Louisville Jockey Club when it conducted its first race meet in 1875. Its first running was held Wednesday, May 19, 1875 as one of four stakes races developed by founder M. Lewis Clark for the track's inaugural meet. The others were the Kentucky Derby, the Clark Handicap and the Falls City Handicap. The Kentucky Oaks is renewed each year on the Friday before the Kentucky Derby, but it is much more than a sister race to the famed "Run for the Roses."

The roster of horses that have won the 1⅛ mile (1811 metres) race in its first 130 years includes some of the greatest fillies in racing history. Three of those races — the Kentucky Derby, the Kentucky Oaks and the Clark — were modeled after Classic races in England. The Kentucky Oaks was fashioned in the image of the English Oaks at Epsom Downs Racecourse.

The distance of that first running of the Kentucky Oaks was 1 ½ miles (2414 metres) and A.B. Lewis & Company's Vinaigrette was the winner. She earned a winning purse of $1,175 and was timed over the 12 furlong (2414 metres) distance in 2:39 ¾.

The victory by Vinaigrette launched a strong tradition for the Kentucky Oaks, which — like the Kentucky Derby — has been renewed each year without interruption since its inaugural running.
Louisvillians once referred to the Oaks as "our Derby," implying that the Derby itself had become the domain of celebrities and out-of-town visitors. In recent years that has changed, as the Oaks has become nearly as popular as the Derby. Indeed, the spectator attendance on "Oaks Day" is usually second only to Derby Day, surpassing attendance at the Preakness Stakes and the Belmont Stakes, as well as the Breeders' Cup.