Iron Constitution (1974–1989) was an American Thoroughbred racehorse owned by Harry T. Mangurian Jr.'s Mockingbird Farm of Ocala, Florida.
Iron Constitution was bred by Thomas Mellon Evans, a prominent Pennsylvania financier and a Thoroughbred racehorse owner and breeder who won the 1981 Kentucky Derby and 1981 Preakness Stakes.
The fractions that day were blistering on the lead, with Jean Cruguet trying to slow Slew down under a "pull", finishing the first quarter mile in :223/5 and the half in :453/5.
[4] Just prior to Pimlico's famous "Clubhouse Turn" Iron Constitution's jockey Jorge Velásquez angled him in and slid between horses to reach the rail.
Iron Constitution was euthanized due to a fractured leg in June 1989 at Graywood, Livonia Center, New York, where he spent his stud career.