Non-flammable characteristic of dry-type cast-resin transformers make them suitable for residential and hospital usages. However, because of resin's property, thermal behavior of these transformers is undesirable, so it is important to analyze their thermal behavior. In this paper temperature distribution of cast-resin transformers is modeled by two different approaches. A FEM-based model which uses experimental-analytical formula for air-cooling vertical ducts and a 3D finite volume based CFD model which is established in the ANSYS CFX software. In order to evaluate and compare the models, the simulation results were compared with the experimental data measured from an 800 kVA transformer. Finally, the influences of some construction parameters and environmental conditions on temperature distribution of cast-resin transformers were discussed. (C) 2011 Elsevier Ltd. All rights reserved.