| State: | OR |
| Type: | OR |
| Route: | 339 |
| Map Custom: | yes |
| Map Notes: | Route 339 highlighted in red |
| Length Mi: | 3.43 |
| Direction A: | South |
| Terminus A: | Milton-Freewater city limits |
| Direction B: | North |
| Terminus B: | State Line Road near Ferndale |
| Established: | 2003 |
| Previous Type: | OR |
| Previous Route: | 335 |
| Next Type: | OR |
| Next Route: | 350 |
Oregon Route 339 (OR 339) is an Oregon state highway running from the Washington state line near Ferndale to Milton-Freewater. OR 339 is known as the Freewater Highway No. 339 (see Oregon highways and routes). It is 3.43miles long and runs north–south, entirely within Umatilla County.
OR 339 was established in 2003 as part of Oregon's project to assign route numbers to highways that previously were not assigned.
OR 339 begins at an intersection with State Line Road approximately one and one half miles north of Ferndale, at the Washington state line, and heads south through Ferndale and Sunnyside. Approximately one-half-mile south of Sunnyside, OR 339 intersects OR 332. OR 339 ends at the Milton-Freewater northern city limit.
OR 339 was assigned to the Freewater Highway in 2003.