Drainage Basin A, is one of the drainage basins of South Africa. The main river in this system is the Limpopo River. It is subdivided into 9 sub-drainage basins.
- A1 is situated along the Botswana border, and is again divided into 3 river basins
- A10A covers the Ngotwane River up to and including the Ngotwane Dam
- A10B covers the Notwane River up to the border with Botswana and it joins the Taung River in Botswana, just before it drains into the Gaborone Dam
- A10C covers the Segakwane River before it crosses the border with Botswana.
- A2 has the Marico River as main river system.
- A21A covers the Hennops River and Rietvlei River up to and including the Rietvlei Dam
- A3 has the Crocodile River as main river system and divided into 11 river basins. Situated off northwest Gauteng and Limpopo province.
- A31A
- A32A
- A32B
- A32C covers the Brakfonteinspruit until it drains into the Molatedi Dam, as well as a short section of the Raswue River, before it crosses the border with Botswana.
- A4 has the Mokolo River as main river system. Includes the Matlabas River, a smaller tributary of the Limpopo.
- A5 has the Lephalala River as main river system.
- A6 has the Mogalakwena River as main river system.
- A7 has the Sand River (Polokwane) as main river system.
- A8 has the Nzhelele River as main river system. Includes the Nwanedi River
- A9 has the Luvuvhu River as main river system.