| Serra dos Reis A State Park | |
| Alt Name: | Parque Estadual Serra dos Reis A |
| Iucn Category: | II |
| Map: | Brazil |
| Relief: | yes |
| Nearest City: | São Francisco do Guaporé, Rondônia |
| Coordinates: | -12.18°N -63.9532°W |
| Designation: | State park |
| Created: | 7 November 1996 |
| Administrator: | Secretaria de Estado do Desenvolvimento Ambiental |
The Serra dos Reis A State Park (Portuguese: Parque Estadual Serra dos Reis A) is a state park in the state of Rondônia, Brazil.
The Serra dos Reis A State Park is divided between the municipalities of Costa Marques (14.17%) and São Francisco do Guaporé (85.83%) in Rondônia.It has an area of .It adjoins the Serra dos Reis State Park along its southern boundary.The park is to the south of the BR-429 highway, east of the town of Costa Marques and north of the Guaporé River, which defines the border with Bolivia.
The Serra dos Reis A State Park was created by decree 7.637 of 7 November 1996 with an area of about in the municipality of Costa Marques.The park was bounded by the Serra dos Reis State Park, created by decree 7.027 of 8 August 1995.The State Department of Environmental Development (SEDAM) was made responsible for administration.