Numerous studies in materials science and chemistry have expanded our understanding of the repellency of water droplets from surfaces. Much of the inspiration for the development of synthetic water-repellent materials came from the examination of water-repellent properties of animals and plants in the natural environment. The hydrological significance of water repellency in the natural environment remains an underexplored research topic. Although the hydrological significance of soil water repellency has become well established in the ecohydrology and water resources literature, fewer studies have examined the significance of leaf water repellency. This review examines the properties of leaf water repellency, the methodologies used to calculate leaf water repellency, the leaf surface properties that promote leaf water repellency, and the significance of leaf water repellency in ecohydrological research. The repellency of a water droplet by a leaf surface is functionally important among plant species and may reflect selective strategies that either favour leaf water uptake in drought-prone environments or promote higher photosynthetic efficiency during prolonged periods of precipitation through higher repellency. Information on the functional significance of leaf water repellency in hydrologic models could enhance our understanding of the delivery of water resources to municipal reservoirs and fill in a missing gap in our understanding of leaf water repellency as a process that influences discharge, and by extension, water resources. Copyright © 2012 John Wiley & Sons, Ltd.