According to MacLysaght's book of SURNAMES OF IRELAND, Dennison is found in the Province of Ulster and Dennis (same name) is found in Cork and Dublin. Don't know what time frame you are searching, but in the Griffith's Valuation (1848-1864) found a few Dennis's in Armagh, Fermanagh and Tyrone. Dennison and Dennisson was found in Armagh, Antrim, Down and Tyrone, with the name most numerous in County Down. In the 1890 Matheson Report of Irish Births, the name Dennison is shown with 6 births in County Armagh. Slan go foill, Margaret (Mairead) >Has anyone heard of the surname Denison in Ulster. If so where, I have >been unable to find any record. > >