| Country: | DEU |
| Type: | B |
| Route: | 242 |
| Map: | B242 Verlauf.svg |
| Length Km: | 124 |
| Direction A: | East |
| Terminus A: | Seesen |
| Direction B: | West |
| Terminus B: | Mansfeld |
| States: | Lower Saxony, Saxony-Anhalt |
The B 242 is a federal highway (German: [[Bundesstraße]]) in Germany. It runs from Seesen to Mansfeld.
The B 242, also known as the Harz High Road (Harzhochstraße), runs right across the Harz mountains in central Germany. From Seesen on the northwestern edge of the Harz near the A 7 motorway it runs through the Upper Harz past Clausthal-Zellerfeld, the High Harz, where it is combined for several kilometres with the B 4, past Braunlage and then through the eastern Harz foothills into Mansfelder Land. There it joins the B 180 east of Klostermansfeld.
An extension of the B 242 via Polleben and Salzmünde to Halle (Saale) is being planned.