Princequillo was the Leading sire in North America for 1957 and 1958 and Leading broodmare sire from 1966 through 1970 and again in 1972 and 1973. Among his daughters' progeny are Mill Reef, Fort Marcy, High Echelon, Triple Crown winner Secretariat, and Secretariat's chief rival Sham. His son Prince John was Leading broodmare sire in 1979, 1980, 1982 and 1986. Princequillo's descendants include, Secretariat, Triple Crown Winner in 1973, Triple Crown winner Seattle Slew and U.S. Horse of the Year winners A.P. Indy and Cigar, the second greatest money winner of all time. Zenyatta, John Henry, California Chrome and American Pharoah are also in his line of progeny. He garnered the nickname Mr. Fixit at stud thanks to his ability to sire foals with good confirmation and soundness.