Age and Breed Requirements
All horses in the Kentucky Derby must be three years old on the day of the race. They must be registered Thoroughbreds recognized by The Jockey Club. Both male horses (colts) and female horses (fillies) are allowed to compete, though fillies rarely enter.
Points-Based Qualification System
Rather than a first-come, first-served entry system, the Derby uses a points system. Horses earn points by finishing in the top positions at qualifying races held throughout the year. These races are designated as Derby prep races. Horses accumulate points based on where they finish, with higher-finishing positions earning more points. The 20 horses with the most points gain entry to the race.
Ownership and Registration Requirements
Horses must be properly registered with The Jockey Club and have valid ownership documentation. Owners must nominate their horses before the deadline, which typically occurs in the fall before the race. There are nomination and entry fees that owners must pay to participate in the Derby.
Physical and Health Standards
All horses must pass veterinary inspections and be in good health to race. They must meet weight requirements set by the race officials. Horses with certain past injuries or health conditions may be disqualified from racing.
Racing Record Requirements
Horses must have raced previously and earned points to qualify. There is no requirement for a specific number of prior races, but horses need to have competed and placed well enough to accumulate sufficient points for entry. Unknown or untested horses are unlikely to qualify through the points system. 
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