  The internal dust extinction in spiral galaxies can affect our understanding
of their structure and morphology, as well as our perception of the distant
universe in the background. The intrinsic properties of the stellar and dust
components can be studied by comparing the observed appearance of a dusty
spiral in the optical with a radiative transfer model. The absorbed starlight
is re-radiated by dust in the FIR/sub-mm. Thus, observations at long
wavelengths allow to put further constraints on the properties of the dust
distribution. I present our Monte Carlo simulations for dust extinction and
emission in galactic disks, discuss the basic ingredients and limitations and
compare them with other solutions for the radiative transfer available in the
literature. I review the current picture of dusty disks that emerges from
radiative transfer studies.
