In this paper, an investigation was carried out to study the effect of water fraction and flow conditions on the flow characteristics of surfactant stabilized water-in-oil emulsion. Pressure drop measurements were conducted in 2.54-cm and 1.27-cm horizontal pipes. The influence of water fraction and the flow conditions on emulsion stability, type, conductivity, droplet size distribution, viscosity and pressure drop were reported. The results showed a significant increase in the emulsion stability, viscosity and pressure drop with increasing water fraction up to 70%. In addition, shear thinning behavior was observed for the emulsions especially at high water fractions. Furthermore, pressure drop measurements of high concentrated emulsions showed pipe diameter dependency especially at high Reynolds (Re) numbers. Moreover, drag reduction was observed with decreasing water fraction. The viscosity of surfactant-stabilized water-in-oil emulsions was modeled with a modified fluidity-additivity model. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.