| Image Coa: | DEU Altendiez COA.svg |
| Coordinates: | 50.3714°N 7.985°W |
| Image Plan: | Altendiez in EMS.svg |
| State: | Rheinland-Pfalz |
| District: | Rhein-Lahn-Kreis |
| Verbandsgemeinde: | Diez |
| Elevation: | 170 |
| Area: | 9.22 |
| Postal Code: | 65624 |
| Area Code: | 06432 |
| Licence: | EMS, DIZ, GOH |
| Gemeindeschlüssel: | 07 1 41 002 |
| Website: | www.altendiez.de |
| Mayor: | Thomas Keßler[1] |
| Leader Term: | 2019 - 24 |
Altendiez is a municipality in the district of Rhein-Lahn, in Rhineland-Palatinate, in western Germany. It belongs to the association community of Diez.