This paper presents a method for solving multiregion transport problems which is a generalization of integral transport theory as typified by the well-known Amouyal-Benoist-Horowitz method. The theorem of uniqueness of the solution of Boltzmann equation is used to reduce the problem to a series of associated problems, the Green's functions of which are supposed to be known, with appropriate sources at region boundaries. A system of integral equations is obtained for the sources. The present paper is restricted to one-speed, plane geometry, and infinite medium problems as associated ones. The numerical results presented appear to be very good compared with other methods. Our method provides the advantage of reducing the number of unknowns by an order of magnitude and can therefore provide a comparable reduction in computing time.