Allenstown is a town in Merrimack County, New Hampshire. Its population at the 2010 census was 4,322. A part of the village of Suncook lies within the town limits. The town is named after Samuel Allen, and it was incorporated in 1831.
About half the town area is covered by Bear Brook State Park. Tourism and recreational activities including camping, hiking, archery and rowing. Important commercial operations in the town include sales, production, transportation and material moving.