Evidence is found over broad regions of the ocean that variations in salinity have sufficiently large effects on sea level such that they may be detectable by an altimeter. The mechanisms involve the salinity variability within the tropical mixed layer, the tropical and subtropical baroclinic response in the main halocline and the barotropic response in the Southern Ocean. All these processes lead to signals in sea level which range between 2 and 10 cm. An important result is that in the western tropical Pacific Ocean the effect of salinity variability on sea level may be equal to the effect of thermal variability. ¿ 1998 American Geophysical Union