This article reviews an integral equation technique to efficiently solve printed structures consisting of conducting patches, slots, and ground planes residing in a stratified medium. The integral equation is cast into a mixed potential form and solved in the space domain. Both the electric and magnetic surface currents are considered as general two-dimensional surface currents with no prescribed or preferred direction. Thus, arbitrary shapes for patches and slots can be considered. After the formulation in the space domain, the integral equation is solved using the method of moments. Theoretical results are compared with measurements for three structures. These structures are: a wide slot antenna excited by a microstrip line; a microstrip line-slot linemicrostrip line transition; and transitions between microstrip lines embedded at different levels of a multilayered media.