The paper reviews the demands made on technology by the potential impact of fibre-optical communication systems. The reasons for the interest in this technology are discussed in terms of discounted cash flow for wideband transmission installation. The primary system requirements are identified and research aimed at developing fibre-optic cable, light sources and terminal sub-systems is described.Some typical system parameters which can reasonably be related to the present state of art are given. It is concluded that there is now little doubt that fibre optic communication will make a major impact on transmission technology. It is further suggested that the greatest impact may be in opening up new fields of telecommunication.