The Lusatian Neisse (; ; ; Upper Sorbian: Lužiska Nysa; Lower Sorbian: Lužyska Nysa) is a long river in Central Europe. It rises in the Jizera Mountains near Nová Ves nad Nisou, Czech Republic, reaching the tripoint with Poland and Germany at Zittau after , and later forming the Polish-German border for a length of . The Lusatian Neisse is a left-bank tributary of the river Oder, into which it flows between Neißemünde-Ratzdorf and Kosarzyn north of the towns of Guben and Gubin.