Recent publication reported that void ratio is not a good state variable for sand with fines. Thus, equivalent granular void ratio, e^* has been proposed to resolve this problem. The Steady State data points in the e^*−log(p^′) space can be described by a single trend irrespective of fines content, f_c, provided f_c≤TFC. This single trend line is referred to equivalent granular steady state line, EG-SSL. However, whether the EG-SSL can be used within the context of critical state soil mechanics (CSSM) for predicting undrained behaviour has to be investigated. An equivalent granular state parameter, ψ^*, defined using EG-SSL as the reference is proposed in this paper. It is found that ψ^* can successfully predict undrained responses of sand with fines in undrained shearing.