The paper assesses the significance of thermal radiation in turbulent non-premixed natural gas flames confined in axisymmetric furnaces. The in-house developed computational model includes simulation of the turbulent flow characteristics, the controlling Mixing and chemical mechanisms as well as radiation modeled via the six-flux and of the P-1 models. A variable absorption coefficient is taken into account for the gaseous combustion mixture based on temperature and composition of the mixture. The results with and without radiation are evaluated as part of the complete prediction procedure involving flow, combustion, convection, and radiation phenomena. The comparative assessment of the two radiation models against experimental data indicates that they can be easily applied in engineering cases, with the P-1 model yielding more accurate results in the case considered. (C) 2007 Elsevier Ltd. All rights reserved.