The effect of cadmium on some parameters of water relations in barley plants (Hordeum vulgare L.) was studied under laboratory conditions. The experiments showed that four day exposure on nutritious solution containing the metal (100 μM) inhibited root growth, caused a reduction in the number and size of stomata, partial closing of the stomatal aperture and decrease in stomatal conductance. These changes inhibited transpiration although there was no significant change in the water content in tissues. The latter fact is obviously connected first of all with reduction in the rate of transpiration, and probably also with the mainly symplastic water transport in cells, characteristic of this species.