The future trends of SOI MOSFETs and the critical issues related to their miniaturization are addressed. The scaling of the gate oxide in Partially Depleted SOI devices and its impact on the floating body effects is discussed based on extensive measurements and simulations. Special dimensional and time-related mechanisms (transient current, history effects, and low frequency noise) are described. The impact of thin buried oxide is analyzed in terms of short-channel effects and self-heating. Ultra-thin films are requested for achieving aggressive performance and scaling. Our data in sub-15 nm films reveal unusual coupling effects. The bias conditions for optimum single-gate and double-gate operation are investigated.