This book presents a boundary element method for heat conduction problems in non-homogeneous media. The method developed contributes to the rapidly evolving field of integral equation methods by providing a technique where a boundary-only integral equation is used to solve field problems governed by a variable-coefficient partial differential equation. Although the authors’ text specifically addresses the heat conduction equation, the proposed method is applicable to a variety of engineering field problems, including flow through porous non-homogeneous media and elasticity in non-homogeneous media.