Nashua's sire was the good, but temperamental, European champion Nasrullah. Nashua's dam was Segula, a good broodmare who has had influence through her female descendants.
Owned by William Woodward, Jr.'s famous Belair Stud in Bowie, Maryland, Nashua was trained by Sunny Jim Fitzsimmons and ridden by jockey Eddie Arcaro. As a two-year-old in 1954 Nashua entered eight races, winning six and finishing second twice, a performance that earned him champion 2-year-old honors. The following year, he earned the Eclipse Award for Horse of the Year.
Following the death of William Woodward, Jr., the Belair Stud horses were auctioned off and Nashua became the first horse to ever sell for more than $1 million. At the end of his 1956 season, after thirty career races with a top three record of 22-4-1, Nashua was retired to stand at stud at Spendthrift Farm in Lexington, Kentucky. Nashua retired as only the second horse to earn more than $1 million. His earnings of $1,288,565 surpassed the great Citation's record and stood as the earnings record until surpassed by Round Table in the autumn of 1958.
In 1965, he was inducted into the National Museum of Racing and Hall of Fame. In The Blood-Horse ranking of the top 100 U.S. thoroughbred champions of the 20th Century, Nashua was ranked 24.
Nashua died in 1982, and is buried at Spendthrift Farm. In the mid-Eighties, the farm commissioned a statue to be raised over him. The sculptress was Lisa Todd, the daughter of Mike Todd and Elizabeth Taylor.