Soil salinity decreased the Ca contents of shoots of two cultivars of barley (Hordeum vulgare L.) grown under field conditions, particularly in younger leaves. Reduction in Ca content was more pronounced in cv. Arivat (the more salt-sensitive cultivar) than in cv. Briggs. In seedlings grown in solution culture, relatively low concentrations of NaCl inhibited the transport of Ca to the shoot. This inhibition was not due to effects of NaCl on Ca influx into the root or on transpiration. We propose that NaCl inhibits Ca transport from root to shoot by interfering with the release of Ca into the root xylem, possibly via an effect on the active loading of Ca into xylem vessels.