In the last half-century the application of scientific advances in irrigation has been largely confined to the developed countries. In the vast irrigated areas of Asia, progress in the adoption of new technology has been disappointing except for the introduction of new crop varieties. The massive expansion in the total irrigated area of Asia has been largely based on traditional technology. The world is waking up to this technological gap and beginning to analyse its causes. The current gap is illustrated by the fact that irrigated cereal yields in Asia are less than half those of the U.S.A. or Australia. In Africa, the gap is even wider. It is argued that many recent technologies, including those of micro-irrigation, systems analysis and automatic control structures, are not applicable to Asia and Africa. We have to research new ways of applying them and we need to expand the science of irrigation in more appropriate forms. Among the needs for scientific advance considered in the paper are improved water management, use of saline groundwater, lower cost methods of subsoil drainage and improved management technology involving wider and better use of communications and management information systems. The paper examines these and other issues and suggests high-priority topics and strategies for research and development.