The Internet has brought about change in the way that public relations is practised. Not only has it provided another channel of communication, but the communication dynamic itself has changed because of the Internet's unique combination of characteristics. Much public relations practice is still posited on dated theories of the system of communication along the linear lines of sender, channel, receiver (with feedback). The public relations professional is there to transmit a message with the purpose of persuading publics to the point of view being promulgated. There have been suggestions that a new model of communication is required in order to explain the Internet medium. This paper re-examines three of the older communication systems models to establish whether there are elements within them that can be helpful in explaining the dynamics of Internet-based communication. The authors use the three models, in turn, to examine this medium by focusing on the message sender, the channel itself and the user of the Internet. The conclusion is that together they can throw valuable light on Internet-based communication and that there are lessons to be drawn from these models that are useful for the contemporary public relations practitioner.