Abstract Sea Surface Salinity (SSS) data have been collected in the tropical Pacific Ocean since 1969. From this data set, relationships of SSS with ENSO have been found in both the western and the eastern Pacific. These have mainly been associated with the presence of the ITCZ and equatorial upwelling. In the Central South Tropical Pacific a surface salinity maximum is formed by a positive Evaporation-Precipitation balance which undergoes seasonal and interannual variations. It is prolonged in the west by a subsurface salinity maximum. During ENSO events, the surface and subsurface salinity maxima expand westward. Initially, the subsurface salinity maximum is strengthened and shoals, but eventually it is driven back eastward by the equatorial jet. Such changes in surface and subsurface salinity need to be included in the scenario of a El Niño event.