罗蓝县（Lorain County, Ohio）是美国俄亥俄州北部的一个县，北隔休伦湖与加拿大安大略省相望。面积2,391平方公里。根据美国2000年人口普查，共有人口284,664人。县治伊利里亚 (Elyria)。

成立于1822年12月26日。县名是早期殖民者赫尔曼·伊利以法国的洛林 (Lorraine)命名。

Lorain County is a county in northeastern Ohio. As of the 2010 census, the population was 301,356. Its county seat is Elyria. The county was created in 1822 and later organized in 1824.

Lorain County is part of the Cleveland-Elyria, OH Metropolitan Statistical Area.