The Green's function solution method is a direct and powerful tool for solving heat transfer problems associated with flow through passages. It is also an equally powerful tool when these passages are filled with saturated porous materials. The capability of the Green's function solution is enhanced when it is used in conjunction with the method of weighted residuals extended for this type of application. This study discusses the calculation of heat transfer to fluids flowing through different porous passages by using this combined methodology. The numerical illustrations include the study of heat transfer in isosceles triangular passages. Also, this methodology is equally applicable when the boundary conditions are of the first, second, or third kind. (C) 2004 Elsevier Ltd. All rights reserved.