annual four-day series of rowing races held the first week in July on the River Thames, at Henley-on-Thames, Oxfordshire, Eng. The regatta was established in 1839; and in 1851 Prince Albert became its patron and gave the event its “royal” prefix. The regulation distance for the races is 1 mile 550 yards (2,100 m). Probably the most significant of the traditional Henley races are the Grand Challenge Cup, the oldest (established in 1839), which usually attracts the world's finest eights (crews using eight oars), and the Diamond Challenge Sculls (1844), one of the world's top single sculls events (one man, two oars). There are several other events, for various types of crews, most of which are open to entries from anywhere in the world.

The American Rowing Association, founded in 1902 to stimulate intercollegiate competition in the U.S., ends its season each year with a regatta at the regulation Henley distance, alternately at Philadelphia and Boston, that has become known as the American Henley. A similar event called the Royal Canadian Henley has been held annually at St. Catharines, Ont., since 1903 (at various sites earlier to 1880). An Australian Henley at Melbourne was first held in 1904.