Water Relations in Membrane Transport in Plants and Animals contains the presentations in a symposium dealing with Water Relations in Membranes in Plants and Animals, during the 27th Annual Fall Meeting of the American Physiological Society held at The University of Pennsylvania, 17-19 August 1976. The purpose of the symposium was to explore the common modes of water regulation in plants and animals. In these proceedings, the mechanisms employed to restrict water flow across plant and metazoan animal cells are described. Putative differences in mechanisms of water regulation retained by plant versus animal cells become inconsequential in the light of the numerous similarities: dependence upon bioelectric potentials maintained across cell membranes, energy dependence of uphill water movement, and solute coupling during water transport. The presentations can be organized into four. The first takes up specific mechanisms of water transport in plants. The second and third parts deal with specific mechanisms in invertebrates and vertebrates, respectively. The fourth part covers generalized mechanisms common to plants and animals.