Woodburn Stud was an American horse breeding farm located in Woodford County, Kentucky about ten miles (16 km) from the city of Lexington. It was established in the 18th century as an original land grant property of General Hugh Mercer to whom it had been granted for his military services during the American Revolutionary War. Robert Alexander (1767–1841), a Scottish immigrant, came to Virginia from Scotland in 1786. Around 1790 he purchased the Mercer estate in Kentucky. Under the guidance of his son, Robert A. Alexander, during the 19th century, Woodburn Stud became the birthplace of Kentucky's Thoroughbred industry.
Robert A. Alexander was the first to establish a systematic design method for horse breeding. Woodburn Stud was home to the stallion Lexington (1850–1875), America's leading sire for sixteen years. Lexington sired numerous champions and winners of major races including, Duke of Magenta, Kentucky and Preakness, for whom the Preakness Stakes is named. Woodburn breeding yielded 18 winners of U.S. Triple Crown race winners and other major winners including Lexington's grandson Foxhall.
Some of the notable Thoroughbreds buried at Woodburn farm include Asteroid (1861–1886), Planet (c. 1855-1875), and Australian (1858–1879), a son of the English Triple Crown winner, West Australian
Although Lexington's success as a sire made Woodburn Stud near synonymous with flat racing Thoroughbreds, in fact during the mid to late 19th century, Woodburn was where the Standardbred horse originated and the farm was best known for these trotting horses for harness racing.
After the death of Robert A. Alexander in 1867, the operation prospered under his brother A. J. Alexander (b. 1824) but after his death it went into decline. By the beginning of the 20th century the farm was no longer in the horse business and had been converted to cattle land.
In 1867, A. J. Alexander bred Preakness who would be purchased by Milton H. Sanford and for whom the Preakness Stakes is named. The American Classic Race winners bred by the Alexanders' Woodburn Stud are:
Today the Woodburn name is long gone but the horse breeding business was revived in 1972 as Airdrie Stud which now operates on 2,500 acres (10 km2), much of which is part of the original Woodburn Stud lands. Airdrie Stud is owned by former Kentucky Governor Brereton Jones and his wife Libby. Mrs. Jones is a descendant of the Alexander family. In 2000, the Airdrie-bred filly Caressing won the Breeders' Cup Juvenile Fillies.