This paper will provide an insight into the use of periphrastic and inflected genitive forms and their frequency in different registers of English. First, a theoretical background on the English case system, particularly the genitive case, will be provided and key guidelines for identifying genitive constructions will be established. Next, the similarity of function and meaning between a noun in the genitive case and the same noun as head of a prepositional phrase with of will be outlined, followed by the semantic types of genitive constructions which demonstrate how this choice between the –s or the of-genitive largely depends on the meaning expressed by the genitive. Apart from the semantic types of genitive, the choice between the ‘s and the of-genitive can also be influenced by other factors and these will in turn be discussed according to their categories (lexical, relational, syntactic, etc.) The core part of this paper will consist of a selection of genitive phrases, divided into inflected and periphrastic genitive constructions, with the purpose of illustrating their frequency of use in the English language. The selection of phrases will be obtained from The Corpus of Contemporary American English web site, with special focus on the spoken and newspaper registers. The last and most important chapter will be dedicated to the presentation and interpretation of results with the purpose of confirming our hypothesis: The ‘s genitive forms with inanimate nouns are used more frequently in the newspaper register than in the register of spoken language.