The Röslau or Rösla (Czech: Reslava) is a right-hand tributary of the river Ohře in northeast Bavaria in Germany.

It is formed from several small tributaries that come together on the eastern slope of the Schneeberg west of the Vordorf Mill (Vordorfermühle) at Trostau in the Russel forest division.

After leaving the steep slopes and high forest on the Schneeberg the Röslau runs past the Vordorf Mill, turns initially southeast to Leupoldsdorf and Tröstau, grazes Wunsiedel and swings gradually in an easterly and northeasterly direction.

East of the village it forms Germany's boundary with the Czech Republic until it discharges into the Eger near Fischern.

Recent research suggests the name combines words meaning "in lively motion, stirring" and "flowing" or "streaming".