This work presents an analytical investigation of two-phase pressure drops during evaporation in horizontal tubes. Based on a comprehensive state-of-the-art review and comparison with two-phase frictional pressure drop prediction methods, it is proven that none of these existing methods were adequate to predict the experimental values presented in Part I. Hence, an analytical study was undertaken in order to develop a new two-phase frictional prediction method. The new model has been developed following a phenomenological approach as the interfacial structure between the phases is taken into account. The recent [Wojtan, L., Ursenbacher, T., Thome, J. R., 2005a. Investigation of flow boiling in horizontal tubes: Part I – a new diabatic two-phase flow pattern map. Int. J. Heat Mass Transf. 48, 2955–2969] map was chosen to provide the corresponding interfacial structure. The new model treats each flow regime separately and then insures a smooth transition at the transition boundary, in agreement with the experimental observations. Next, based on a statistical comparison, it is concluded that the new two-phase frictional pressure drop flow pattern map based model successfully predicts the new experimental database and captures the numerous trends observed in the data.