Presented at the 2014 Ocean Sciences MeetingSMOS mission monitors sea surface salinity (SSS) over the global ocean for almost 4 years. Rms difference between SMOS SSS averaged over 100km-1month and in situ (ship and ARGO) SSS is about 0.2 in subtropical regions and less than 0.5 between 45°N and 45°S. After reviewing large scale accuracy of SMOS SSS, we focus on variability at shorter scales than the ones sampled by the ARGO array. Individual SMOS SSS at 43km resolution are very noisy, as expected from the interferometry technique of the SMOS-MIRAS instrument. The observed variability within 100km-1month is very consistent with instrumental noise except in regions affected by land contamination, by radio frequency interferences or caracterized by large natural SSS variability, like strong precipitation areas. For a mean rain rate of about 0.5mm/hr over 100km-1month, SMOS filtered from instrumental noise indicates a SSS natural variability on the order of 0.6. This order of magnitude is compared, in a few well sampled areas, with variability observed in situ by drifters and by ARGO profilers: a large SSS variability is linked to the intermittency of precipitation events.