In Bulgarian a specific type of indefinite pronouns (formed with E-) has been observed. Their role is not only to substitute the original information in the reported speech, but also to reduce it and make it "unspecific". In Russian the same role is undertaken by the demonstrative pronouns of the type makou-mo, mom-mo, mozda-mo Very often these pronouns are semantically ambiguous. The current paper presents a contrastive corpus study of Bulgarian and Russian forms of the pronouns in question. The Bulgarian-Russian equivalents are described in their nominal, adjectival and adverbial usages. The similarities and differences are outlined in the structure of the "unspecifying" nominal phrases, in the position of the elements as well as in their functions.