TN3 or TN-3 may refer to:
Tn3 transposon, a mobile genetic element found in prokaryotes Tennessee's 3rd congressional district Tennessee State Route 3 Honda TNIII, a pickup truck TN3, a postcode district in Tunbridge Wells, England; see TN postcode area
See also The Tennessee Three (band), Johnny Cash's backing band Tennessee 3, legislators who faced the 2023 Tennessee House of Representatives expulsions