The effect of scaling (1 ?m to 0 .09 ?m) on the non-quasi-static (NQS)behaviour of the MOSFET has bee studied using process and device simulation. It is shown that under fixed gate (Vgs) and drain (Vds) bias voltages the NQS transition frequency (fNQS) scales as 1/Leff rather than 1/L2 eff due to velocity saturation effect. However under the practical scaling guidelines, considering the scaling of supply voltage as well, fNQS shows turn around effect at the sub 100nm regime. The relation between unity gain frequency (ft) and fNQS is also evaluated and it is shown that ft and fNQS have similar trends with scaling.