EN
The aim of this article is to present a construction consisting of a secondary preposition 'prostrednictvim'i and genitive case, its frequency, meaning, and typical uses in contemporary Czech. The research was conducted on the material (2532 certificates) derived from the journalistic part of the electronic corpus SYN2005. Construction 'prostrednictvim S(gen)' is commonly used as a variant of a synthetic instrumental case in a syntactic position of an instrument. It is frequently employed in texts from such fields as informatics, telecommunication, media, economics, finance and administration. The use of the analytic form instead of instrumental case do not contribute a new meaning to the sentence, but makes it more concrete. The expansion of prepositional constructions, currently observed in Slavonic languages, may be considered as a part of a process that leads, on the other hand, to specialize meanings of a variant language means and, on the other, to transformation of flectional language system into more analytic one.