Lenjan County (Persian: شهرستان لنجان‎‎) is a county in Isfahan Province in Iran. The capital of the county is Zarrin Shahr (Riz-e Lenjan). Lenjan County is also the location of Isfahan Steel Mill. It is located on the banks of the Zayandeh River, which the largest river in Isfahan Province. Farming is an important source of income, and the most important product in Lenjan is rice. At the 2006 census, the county's population was 225,559, in 58,232 families.