| Native Name: | Bezirk Tamsweg |
| Native Name Lang: | de |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Austria |
| Subdivision Type1: | State |
| Subdivision Name1: | Salzburg |
| Subdivision Type2: | Number of municipalities |
| Subdivision Name2: | 15 |
| Seat Type: | Verwaltungssitz |
| Seat: | Tamsweg |
| Leader Title: | Bezirkshauptfrau |
| Leader Name: | Michaela Rohrmoser |
| Unit Pref: | Metric |
| Area Total Km2: | 1,019.65 |
| Population Total: | 20,437 |
| Population As Of: | 2023 |
| Population Density Km2: | auto |
| Timezone1: | CET |
| Utc Offset1: | +01:00 |
| Timezone1 Dst: | CEST |
| Utc Offset1 Dst: | +02:00 |
| Iso Code: | AT-505 |
| Blank Name Sec1: | NUTS code |
Bezirk Tamsweg is an administrative district (Bezirk) in the federal state of Salzburg, Austria. It is congruent with the Lungau region (in German pronounced as /ˈlʊŋˌɡaʊ̯/). The administrative centre of the district is Tamsweg.
The area of the Lungau plateau is 1,019.65 km2, with a population of 20,437 (Jan. 1, 2023), and population density 20 persons per km2. It is located within the Central Eastern Alps, confined by the Hohe Tauern (High Tauern) range in the west, the Niedere Tauern (Low Tauern) in the north, and the Gurktal Alps (Nock Mountains) in the south.
The region is separated from the Salzburg Pongau region by the Radstädter Tauern Pass crossing the Niedere Tauern. In the south, the Katschberg Pass road leads to the neighbouring state of Carinthia. Since 1974, the Tauern Autobahn underpasses both ranges via the Tauern Road Tunnel and the Katschberg Tunnel. In the east, the upper river Mur, originating near Muhr, flows towards Murau in Styria, accompanied by the narrow-gauge Taurach Railway and the Mur Valley Railway.
Beside some pastoral economy, Lungau largely depends on tourism.
The district is divided into 15 municipalities, four of them are market towns.
(population numbers Jan. 1, 2023)