Cool Stars 14 - Submitted Abstract # 176 This version created on 05 October 2006 X-ray variability in main sequence field stars Javier Lopez-Santiago, INAF - Osservatorio Astronomico di Palermo Beate Stelzer, INAF - Osservatorio Astronomico di Palermo Giusi Micela, INAF - Osservatorio Astronomico di Palermo Salvatore Sciortino, INAF - Osservatorio Astronomico di Palermo We present a systematic study on the X-ray variability in the coronal emission of main-sequence field stars. The light curves of the stars in the Bright Source Sample (BSS) of XMM-Newton have been analyzed using an automated procedure for revealing flares and detecting variability. We determine the total number of flares and intensity and compare our results with those obtained for younger stellar samples. ----------------------------------