Deerfield is a town in Rockingham County, New Hampshire, United States. The population was 4,280 at the 2010 census. Deerfield is home to the annual Deerfield Fair.
Deerfield was originally part of Nottingham. In 1756, residents petitioned for organization of a separate parish, but were denied. In 1765, while a second petition was pending, two local hunters presented Colonial Governor Benning Wentworth with a deer. Permission was granted, and "Deerfield" was incorporated in 1766. The incorporation act for Deerfield was signed by three members of the Leavitt family, including Capt. Samuel who later served as one of the town's first selectmen. Leavitts Hill in Deerfield was named for the family, who first settled in nearby Exeter.
"Deerfield Parade," a hilltop district first settled about 1740, was located on the early postal route between Concord and Portsmouth.