Qaen County (Persian: شهرستان قائن‎, also Romanized as Ghayen) is a county in South Khorasan Province in Iran. The capital of the county is Qaen. At the 2006 census, the county's population was 137,357, in 35,783 families (including those portions subsequently detached to form Zirkuh County); excluding those parts, the population in 2006 was 99,228, in 26,444 families. The county consists of three districts: Central District, Nimbeluk District, and Sedeh District.