The studies regarding information structure and its distribution in sentences are traced back to works of Prague School linguists such as Mathesius in 1920s. Recently, the issue of information structure has been dealt with by functionalists. In Role and Reference Grammar (RRG), information structure constitutes one of the main components of syntax. In this theory, information structure is mainly based on the Lambrechtiyan information structure which regards the formal structure of sentences as highly related to the discourse-pragmatic functions. Information structure investigates the way information is structured in clauses and sentences. This paper aims at dealing with information structure in interrogative sentences according to RRG. At first a brief introduction to works on information structure and RRG is presented. Then the theory is applied briefly to Persian language declaratives and dominantly to interrogatives.