This study shows that the scattering intensity by a single fiber having a large size parameter and a large absorption index can be approximated by superimposition of the diffraction intensity by a rectangular aperture and the specular reflection intensity off the fiber surface. Using this approximation, the method for determining the radiative characteristics have been derived. By extending this method, we have also derived the radiative characteristics of fibers having a diffuse surface. Furthermore, we also use the resultant radiative characteristics to estimate the radiative properties of media having randomly oriented fibers and radiation transfer in the media. (C) 2000 Elsevier Science Ltd. All rights reserved.