| Lao River | |
| Map: | Topography of northern Thailand.png |
| Subdivision Type1: | Country |
| Subdivision Name1: | Thailand |
| Subdivision Type2: | State |
| Subdivision Name2: | Chiang Rai Province |
| Subdivision Type4: | District |
| Subdivision Name4: | Wiang Pa Pao, Mae Suai, Mae Lao, Mueang Chiang Rai |
| Subdivision Type5: | City |
| Subdivision Name5: | Chiang Rai city |
| Length: | 206km (128miles) |
| Discharge1 Location: | Mae Lao District |
| Discharge1 Min: | 0.3m3/s |
| Discharge1 Avg: | 28m3/s |
| Discharge1 Max: | 451m3/s |
| Discharge2 Location: | Mae Suai District |
| Discharge2 Avg: | 34m3/s |
| Source1 Location: | Phi Pan Nam Range, Chiang Rai Province, Thailand |
| Mouth: | Kok River |
| Mouth Location: | Sum Pratu, Chiang Rai Province |
| Mouth Coordinates: | 19.9264°N 99.8992°W |
| Mouth Elevation: | 386m (1,266feet) |
| Basin Size: | 3224km2 |
| Tributaries Left: | Suai River |
The Lao River or Mae Lao River (Thai: น้ำแม่ลาว,, in Thai pronounced as /náːm mɛ̂ː lāːw/) is a river in Chiang Rai Province, Northern Thailand. It is a tributary of the Kok River, with its mouth near Sum Pratu in Mueang Chiang Rai District.[1] This river gives its name to the Mae Lao District.
The Lao River originates in the Phi Pan Nam Range[2] and flows initially northwards across Wiang Pa Pao District and then northeastwards through the districts of Mae Suai, Mae Lao and Mueang Chiang Rai passing just south of Chiang Rai city. The Suai River, which gives its name to the Mae Suai District, is one of the main tributaries of the Lao River.