1791 in sports

1791 in sports describes the year's events in world sport.

Baseball
Earliest known reference
 * The broken window by-law in Pittsfield, Massachusetts prohibited "baseball" and other ball games within 80 yards of the new meeting house, the earliest known reference to "baseball" in North America.

Boxing
Events
 * 17 January — "Big Ben" Brain defeated Tom Johnson at Wrotham in the 18th round of a fight lasting 21 minutes to claim the Championship of England. Brain held the title until his death from cirrhosis of the liver in 1794.

Cricket
Events England
 * Most runs – Billy Beldham 532
 * Most wickets – Charles Cumberland 41

Horse racing
England
 * The Derby – Eager
 * The Oaks – Portia
 * St Leger Stakes – Young Traveller