A Symposium on "Combinatorial Structures and their Applications" was held at Villa Madruzeo (Cognola di Trento), on October 20 - 25, 1980. The meeting was promoted and sponsored by the "Centro Interuniveritario per la Ricerca Matematica" (C.I.R.M.) of the "Universita" di Trento" for the purpose of offering an intense week of joint scientific activity to some outstanding scientists and a group of younger researchers. The enthusiastic co-operation of all participants made the Conference a great success.