Thoroughbred broodmares are the foundation of a successful racing operation. This study estimated the impact of breeding, racing, and market characteristics on broodmare auction prices. Data represent 604 in-foal broodmares sold in Keeneland’s 2005 sale. Prices were highly responsive to the sire’s stud fee, the broodmare’s age, and progeny performance in graded stakes races, with pronounced day-of-sale effects. The stud fee marginal value was substantially lower than one break-even estimate, suggesting possible disincentives for investment in stallion services. Out-of-sample forecasts were far superior to naïve forecasts but were not accurate enough to use in isolation from other decision aids.