The paper is concerned with the effect of applied macrostress on the magnetic characteristics of pipeline steels. Magnetic hysteresis parameters are examined as a function of tensile stress, tangential stress, and internal pressure. The study is performed on the hot-rolled 1010 steel alloyed with Mn and Si, widely used in Russia, on the X42SS steel designed specially for operation in hydrogen-containing media and on the X70 steel produced by controlled rolling and intended for heavy-duty trunk pipelines. The results obtained are discussed in terms of the development of nondestructive physical techniques for the diagnosis of the current state of pipe material in course of operation.