This paper presents a new and simple compact model for the intrinsic metal oxide semiconductor (MOS) transistor, which accurately takes into account the non quasistatic (NQS) effects. This is done without any additional assumption or simplification than those required in the derivation of the classical description of the MOS channel charge. Moreover, the model is valid from weak to strong inversion and nonsaturation to saturation. The theoretical results are in very good agreement with measured data performed on devices of various channel length, from 300 μm down to 0.5 μm, and in various modes of operation.