Water permeability of oil layers in a series of water/hydrocarbon/water emulsions has been studied microscopically by measuring the rate of change in the size of the dispersed globules. A range of values, from 2 × 10 −4 to 8 × 10 −4 cm sec −1, has been obtained for the water permeation coefficient calculated by measuring the water flux occurring when various concentration gradients of glucose exist across the oil layer. The permeation coefficients scattered within the above range due to variations in the samples, such as oil layers made of different hydrocarbon preparations, different concentrations of the lipophilic emulsifying agent (Span 80), and various magnitudes of the osmotic pressure gradient between the aqueous dispersed compartments and the aqueous suspending medium. After comparing the permeation coefficient obtained in this study with those of lipid membrane systems, it seems that the oil layers in the W/O/W emulsions may be composed of multilamellar layers of the lipophilic emulsifying agent used for the emulsion preparation.