A two-phase flow of a gas and a non-Newtonian liquid in a pipe enables a significant reduction in the average pressure gradient to be reached, which is of great practical importance in transporting non-Newtonian Liquids. In the literature, a limited amount of information is available concerning the determination of pressure drop in two-phase flow of non-Newtonian liquids. Proposed equations describing two-phase pressure drop are valid in a very narrow range of gas and liquid superficial velocities. In this paper a semi-theoretical general method of correlation of experimental data concerning single and two-phase flow of gas and non-Newtonian liquid in a pipe is presented.