Rockcastle County is part of the Richmond-Berea, KY Micropolitan Statistical Area, which is also included in the Lexington-Fayette–Richmond–Frankfort, KY combined statistical area.

[4] As of the census of 2000, there were 16,582 people, 6,544 households, and 4,764 families residing in the county.

There were 7,353 housing units at an average density of 23 per square mile (8.9/km2).

The racial makeup of the county was 98.81% White, 0.14% Black or African American, 0.24% Native American, 0.13% Asian, 0.01% Pacific Islander, 0.04% from other races, and 0.63% from two or more races.

24.40% of all households were made up of individuals, and 10.70% had someone living alone who was 65 years of age or older.