The Vardar (or Axios, the ancient and current Greek name of the river, being pre-Slavic) is the principal river of the Macedonian region of south-eastern Europe. It is 388 km long, and drains an area of around 25,000 km².

The river begins at Vrutok , a few kilometers north of Tetovo in Republic of Macedonia. It passes through Skopje, crosses the Greek border and flows into the Aegean Sea in Central Macedonia west of Thessaloniki in northern Greece.

The Vardar basin includes 80% of the territory of the Republic of Macedonia.