A modified MHV1 mixing rule was proposed which relaxed the limitation of the MHV1 mixing rule for reproduction of H-E from the G(E) model incorporated. The SRK EOS with the proposed mixing rule coupled with the modified UNIFAC model gives good low-pressure H-E prediction for 23 systems tested. The accuracy is much better than that with the original MHV1 mixing rule, and is comparable to that of the modified UNIFAC model incorporated. The proposed mixing rule was further applied to predict high pressure H-E using the existing modified UNIFAC parameters. The results show that it works well for high-pressure systems without losing predictive accuracy compared to that of low-pressure ones.