Objective: Terrestrial amphibians take up water from the environment through the ventral skin which is pressed tightly against the rehydration source. When dehydrated, toads respond to ionic and osmotic properties of water in potential rehydration sources. Thus, when exposed to high NaCl concentrations (>125 mM) the time showing hydration behavior is significantly reduced relative to distilled water. Similarly, hydration behavior time is strongly reduced when the animals are presented with hyperosmotic (500 mM) mannitol. Methods: We used intracellular microelectrodes in combination with Ussing- chamber technique to measure the basolateral membrane potential (V_b) in cells of isolated toad (Bufo bufo) skin epithelium exposed to distilled water and hyperosmotic solutions known to reduce water absorption behavior. The afferent nerve activity of spinal nerve #6 was recorded with extracellular electrodes when the ventral skin was exposed to the above mentioned solutions. Results: The intracellular microelectrodes studies indicated that exposure of the isolated skin epithelium to Ringer made hyperosmotic with 207 mM mannitol caused a depolarization of V_b of skin keratinocytes similar to that of 250 mM NaCl. The data from the neural recordings indicated that Ringer elicits a neural response significantly greater than distilled water but comparable to 250 mM NaCl while 500 mM NaCl elicited a substantially larger neural response. Interestingly, the neural responses to the same solutions were often amplified by pre-treatment with 500 mM mannitol, significantly so with 500 mM NaCl. Conclusion: Our data indicate that V_b appears sensitive to osmotic as well as ionic stimuli and that the neural response associated with water absorption behavior is determined partly by ionic composition and partly by osmotic strength, and that the ventral skin have chemosensory properties analogous to the mammalian taste bud epithelium.