| Grassau | |
| Type: | Stadtteil |
| Town: | Bismark |
| Coordinates: | 52.6667°N 52°W |
| State: | Sachsen-Anhalt |
| District: | Stendal |
| Elevation: | 44 |
| Area: | 16.17 |
| Population: | 288 |
| Stand: | 2006-12-31 |
| Postal Code: | 39579 |
| Area Code: | 039324 |
| Website: | www.stadt-bismark.de/grassau |
Grassau is a village and a former municipality in the district of Stendal, in Saxony-Anhalt, Germany. Since 1 January 2010, it is part of the town Bismark.