A distance-function-based Cartesian grid (DIFCA) method is presented for conduction heat transfer in irregular geometries. The irregular geometries are identified by distance functions. The finite-volume method is used to discretize the heat conduction equation. Non-zero departure from regular geometries terms are added to the discretization equations for the control volumes bisected by irregular boundaries. With these additional departure terms, the existing Cartesian finite-volume solver call be modified easily to model heat conduction in irregular geometries. Given boundary temperatures, given boundary fluxes and convective heat transfer at irregular boundaries are considered. Non-zero heat generation is also modeled. The proposed procedure is validated against eight test cases where good agreements are achieved. (C) 2007 Elsevier Ltd. All rights reserved.