is a borough in Fayette County, Pennsylvania, United States. The population was 854 at the 2000 census. It is served by the Albert Gallatin Area School District. The town's largest employer is a small wire producing plant run by Nelson Steel.
Smithfield is located at (39.799664, -79.808197). According to the United States Census Bureau, the borough has a total area of 0.7 square miles (1.8 km²), all of it land.