The article discusses the qualitative and quantitative results from a corpus-based research into the constituents of English alternative interrogative structures (EAISs) and their grammatical functions within the clause. The study has shown that the most typical functions of the EAISs are those of direct object, adjunct and subject-oriented predicative complement. The EAISs often represent a binary unmixed coordination of noun phrases, prepositional phrases or (closed) interrogative subordinate clauses. However, there are also EAISs whose constituents belong to different syntactic categories. Still other EAISs have their final constituent unexpressed. The constituents most often occur within the boundaries of the same sentence.