Łęknica [wɛŋkˈɲit͡sa] (German: Lugknitz; Upper Sorbian: Wjeska, pronounced [ˈwʲɛska]) is a border town in western Poland, one of the two gminas of Żary County in Lubusz Voivodeship.

The town is situated in the Polish part of the historic Upper Lusatia region, in the broad valley of the Neisse river, which forms the border with Germany.

A bridge across the river connects it with the opposite German town of Bad Muskau, another border crossing in the south leads to Krauschwitz.

According to the 1635 Peace of Prague, Lugknitz together with Upper Lusatia passed from the Bohemian Crown to the Electorate of Saxony and from 1697 to 1763 it was also under the rule of Polish kings in personal union.

The town was separated from Bad Muskau by the new state border along the Oder–Neisse line, the remaining German population was expelled and the place was gradually settled with Polish military veterans, refugees, people returning from forced labour in Germany, people repatriated from France, Belgium and in 1958, 18 families repatriated from the Soviet Union settled in the city.