The Nišava or Nishava is a river in Bulgaria and Serbia, a right tributary, and with a length of 218 kilometres (135 mi) also the longest one, of the South Morava.

The South Morava is a river in eastern Kosovo and in southern Serbia, which represents the shorter headwater of Great Morava. Today, it is 295 kilometres (183 mi) long, including its source river Binačka Morava. It flows generally in the south to north direction, from the Macedonian border to Kosovo and onwards to Central Serbia, where it meets West Morava at Stalać, to create Great Morava.