Lerna is a village in Coles County, Illinois, United States. The population was 286 at the 2010 census. It is part of the Charleston–Mattoon Micropolitan Statistical Area. Thomas Lincoln, father of President Abraham Lincoln, spent the later part of his life on a homestead a few miles away, preserved today as the Lincoln Log Cabin State Historic Site. Thomas Lincoln and his second wife Sarah Bush Lincoln are buried in Shiloh Cemetery south of town.
Lerna is located at 39°25′5″N 88°17′20″W (39.417943, -88.288957).
According to the 2010 census, Lerna has a total area of 0.12 square miles (0.31 km2), all land.
As of the census of 2000, there were 322 people, 112 households, and 81 families residing in the village. The population density was 2,761.1 people per square mile (1,036.0/km2). There were 131 housing units at an average density of 1,123.3 per square mile (421.5/km2). The racial makeup of the village was 98.76% White, and 1.24% from two or more races. Hispanic or Latino of any race were 0.62% of the population.