International audienceLow frequency noise measurements were performed in n-channel UTBOX transistors fabricated on silicon on insulator (SOI) substrates. The noise spectra contain 1/f and Lorentzian components; it was found that the carrier number fluctuations are responsible for the 1/f noise; the variation of the low frequency noise versus temperature permits to identify traps in the silicon film and to make a correlation between the observed traps and some technological steps