Low frequency noise in Fully Depleted and Double Gate SOI-MOSFETs has been studied and compared for different front and back-gate voltages with special emphasis on the coupling effect. Taking into account the coupling effect as the only parameter affecting the noise level for different back-gate voltages in multi-gate devices explains very well the experimental results obtained for the Fully Depleted devices where the silicon film thickness is 15 nm. In the Double Gate devices where the silicon film is just 6 nm, the effect of the back-gate bias on the noise level is the opposite to that in the Fully Depleted ones. It has been shown that as the carriers are pushed away from the Si/SiO2 interfaces, their reduced amount of tunneling in the oxide traps decreases the noise level. Simulations have also been carried out to give an overview of the effect of the film thickness on the noise level when the back-gate bias is changed. (c) 2007 Elsevier Ltd. All rights reserved.