The purpose of this article is a critical analysis of the definitions and classifications of question words in contemporary German grammar and grammatical-syntactical papers. In communicative situations, the users of the language are employing various interrogative constructions. Therefore, it is of a great importance to be able to identify and classify interrogative sentences in the language. Unfortunately, most of the investigated grammatical theses, which simply refer to the lack of word comprehension and the problematical approach to parts of speech in general, do not present a fully satisfactory explanation of the concept of question words. From this perspective, the author suggests basing the definition and classification of question words on the linguistic theory of Józef Darski, who presents a new solution to the problem of parts of speech resulting in a precise and exact definition of question words.