
Ruan Lanihorne is a civil parish and village in Cornwall, England, United Kingdom. The village is situated approximately four miles east-southeast of Truro between the River Fal and its tributary the Ruan River.
Ruanlanihorne, as the parish is spelt, is entirely rural in character with wooded areas in the river valleys. It is bounded to the north by Tregoney parish, to the east by Veryan parish, to the south by Philleigh parish and to the west by St Michael Penkevil parish. Apart from the church town of Ruan Lanihorne, the only other settlements of any size are in the south of the parish: Treworga and Ruan High Lanes which is right on the parish's boundary with Veryan.
The parish is in the Truro Registration District and the population was 250 in the 2001 census.