Entrainment fraction is one of the key parameters in many applications including wellbore and flow line design, separator design and wellbore loading and many others. Its prediction is important for the estimation of pressure drop, liquid holdup and dry-out in annular flow. The available and widely used maximum fraction of entrainment models have failed to predict the maximum entrainment fraction at low liquid Reynolds number. In this paper a new methodology of modeling the entrainment fraction, containing only two constants, is proposed. The proposed new methodology and procedure was found to predict the experimental data available in the literature very well. Furthermore, an equation for the maximum fraction of entrainment was developed. The proposed maximum entrainment fraction equation predicted more accurately than the equations found in the literature. (C) 2011 Elsevier Ltd. All rights reserved.