EN
Phraseological units are an integral part of foreign language teaching. The present paper is an attempt to improve and describe the state of selected errors made by learners when they use idioms as fixed and restricted word combinations in language. The aim of the paper is to explain selected errors in written texts produced by learners of German as a foreign language in the neophilological education. It is argued that the use of the mother tongue with the lack of knowledge of the foreign cultural background is the reason for the lexical errors when producing phraseological units in a foreign language. Errors are made because learners have not acquired sufficient linguistic und cultural knowledge to produce the given phraseological units correctly. The learners make use of their Polish knowledge in German production. They produce lexical calques that do not exist in German. The mother tongue influences cultural patterns of thought and perception through a culture-specific segmentation of the extralinguistic reality. Errors of this type are a result of the incomprehensibility and/ or misunderstanding of cultural differences between languages.