Ruthin Poor Law Union was formed in 1837, its operation overseen by an elected Board of Guardians, representing its constituent parishes of Aberchwiler, Clocaenog, Derwen, Efenechtyd, Gyffylliog, Llanarmon-yn-Iâl, Llanbedr Dyffryn Clwyd, Llandegla, Llandyrnog, Llanelidan, Llanfair Dyffryn Clwyd, Llanferres, Llanfwrog, Llangwyfan, Llangynhafal, Llanrhaeadr-yng-Nghinmeirch, Llan-rhudd, Llanychan, Llanynys, Nantglyn and Ruthin. The Board of Guardians responsible for the Union had other duties, including the registration of births, marriages and deaths, vaccinations, assessments of rates, sanitation, school attendance and infant life protection. By the Local Government Act 1929, Unions were abolished and their duties transferred to County Councils, responsibility for the poor being transferred to the Public Assistance Committee until 1948.
Very few Ruthin workhouse records have survived.
Records of Ruthin Union, 1837-1903, including minutes, 1837-1844, lists of Guardians and officers, 1886-1902; Ruthin Rural Sanitary Authority minutes, 1888-1896; and accounts, 1891-1903.