A new locality of Temnothorax affinis (Mayr), a Euro-Caucasian xerothermophilous dendrobiotic ant species rare in Central Europe, is reported from Poland; until recently it was regarded as probably extinct in Poland. Single workers were collected from an oak trunk of an old oak in the Cedynia Landscape Park (Pomeranian Lake District, north-western Poland). This locality is one of northernmost known sites of T. affinis.