Sinoe is one of Liberia's 15 counties and it has 17 districts. Greenville is the county's capital.
As of the 2008 Census, it had a population of 104,932, making it one of the least populous counties in Liberia.
As it is also Liberia's third-largest county in terms of area, it is accordingly the second least dense in terms of population density after Gbarpolu County. The Superintendent is J. Milton Teahjay.
The districts of Sinoe County are: