Sodium-deficient rats display an appetite for solutions that humans judge as salty tasting whether or not the solutions contain sodium salts. When offered a choice between a pair of sodium salts, sodium-deficient rats generally preferred the more salty tasting. They tended to do the same for a pair of non-sodium salts and for a pair of sodium and non-sodium salts. The results show that human psychophysical judgments of saltiness are a good predictor of the choices that rats will make when sodium deficient--the more salty, the more preferred. The data support the thesis that the appetite of the sodium-deficient rat is not for sodium but for a salty taste.