Kahyasi (2 April 1985 – 2008) was an Irish-bred and British-trained Thoroughbred racehorse. He won the first five races of his seven-race career, including the Epsom Derby and the Irish Derby as a three-year-old in 1988.
Kahyasi was a small, dark-coated bay horse bred by his owner HH Aga Khan IV at his stud in Ireland. His sire, Ile de Bourbon, was best known for his win in the 1978 King George VI and Queen Elizabeth Stakes. Kahyasi was trained by Luca Cumani at his Bedford House stable Newmarket, Suffolk during his racing career and was ridden in all his races by Ray Cochrane.
Kayasi won the Soham House Stakes at Newmarket in his only race as a two-year-old in 1987. Although the race was a minor one, Ray Cochrane later explained that he and Cumani were "excited" about the colt, and considered him a Derby prospect.
Kahyasi made his three-year-old debut in the Harvester Stakes at Sandown in April. He started the 2/5 favourite and won by two lengths from his five opponents, to whom he was conceding five pounds. On his next start two weeks later he was moved up to Group Three class for the Lingfield Derby Trial. He again started odds-on favourite and won by two lengths from Insan.