An analytical model to study the degradation of body factor (gamma) and subthreshold factor (S) of short channel bulk MOSFETs have been developed and the expression for body factor of short channel devices is derived. Modified relation between S and gamma factors has also been obtained and a correction factor gamma(s) is found which maintained the conventional relation in spite of the degradation of these two parameters in short channel devices. Results obtained are found in good approximation with 2D simulated data. (C) 2004 Elsevier Ltd. All rights reserved.