The lack of freshwater in arid and semi-arid regions makes brackish/marginal water a valuable alternative source of water for irrigation. The use of brackish water in irrigation could ensure high-yield, good quality, efficient and sustainable agricultural development if appropriate management strategies are adopted where natural conditions are favourable. This chapter discusses the following aspects: use of brackish water in irrigation and related issues, challenges and management strategies when irrigating with brackish water to achieve productivity and sustainability, research and results from using brackish water in irrigation, case studies from selected countries, future trends in research for the use of brackish water in irrigation and sources for further related information.