Aroko, the use of material objects packaged together in specific ways was the traditional system of sending messages to people among the Yoruba people in the past. This present study of Aroko system is based on the principle that an event has its place in a system, and that the value or function of such an event depends and derives from the relations it contract with other events in the system. Against the ecological background of the Yoruba country the choice of certain vegetational, animal or other resources in the area could be justified as man can only use the resources available to him. Three elements of Aroko namely, the Sender, the Aroko, (materials/objects) and the Receiver have to operate within an encompassing element, the Context to make an Aroko meaningful. Three type s of Aroko, the Casual, the Formal and the Classified /Highly coded Aroko are identified with illustrations of the various functions of Aroko in the Yoruba culture. The paper concludes with problems of the use of Aroko, and suggestions on how Aroko system could be developed or mordernised as it is still in use even now although in restricted cases despite the ever-growing level of literacy.