Drain current transients in floating-body SOI MOSFETs are of considerable interest for possible application for capacitor-less dynamic access random memories. For maximum refresh time of such memories, it is important that the carrier lifetime in the Si film of such devices be high or the leakage current be low. We present here a detailed study, both experimental and by simulation, of the measurements of drain current transients that are commonly used to extract the carrier lifetime, using p-film-p-substrate pseudo-MOSFETs. In contrast to other papers in this field, we include the role of the substrate in such transients and find the substrate to dominate the drain current transient. Previous studies have largely neglected the substrate. (C) 2009 Elsevier Ltd. All rights reserved.