The Rabnitz () is a river in eastern Austria and northwestern Hungary. Its basin area is .
The Rabnitz is formed at the confluence of its two headstreams Spratzbach and Thalbach near Hollenthon in Lower Austria. It flows towards the east through Burgenland, and enters Hungary (Gyà Âr-Moson-Sopron County) near Répcevis. It receives the Hanság-fà Âcsatorna, the canal that drains the Neusiedler See, from the left, after that changes Hungarian name to Rábca from Répce. It discharges into the Moson branch of the Danube near Gyà Âr.