| State: | SC |
| Type: | SC |
| Route: | 340 |
| Map Custom: | yes |
| Length Mi: | 10.990 |
| Length Round: | 3 |
| Length Ref: | [1] |
| Direction A: | South |
| Terminus A: | near Timmonsville |
| Junction: |
|
| Direction B: | North |
| Terminus B: | in Darlington |
| Counties: | Darlington |
| Previous Type: | SC |
| Previous Route: | 336 |
| Next Type: | SC |
| Next Route: | 341 |
South Carolina Highway 340 (SC 340) is a 10.99adj=midNaNadj=mid state highway in the U.S. state of South Carolina. The highway connects the Timmonsville area with Darlington.
SC 340 begins at an intersection with SC 403 (Oates Highway) north-northwest of Timmonsville, within Darlington County. It travels to the northeast and crosses Middle Swamp and Myrtle Branch before an interchange with Interchange 20 (I-20). It crosses over Jeffries Creek and High Hill Creek before entering the city limits of Darlington. There, it intersects U.S. Route 52 (US 52; Governor Williams Highway). It crosses some railroad tracks before it meets its northern terminus, an intersection with SC 34 (Pearl Street).