  We use the far-UV (FUV) and near-UV (NUV) images of M83 obtained by GALEX to
compute the radial profile of the UV spectral slope in the star forming disk.
We briefly present a model of its chemical evolution which allows us to obtain
realistic intrinsic properties of the stellar populations. Using corollary
data, we also compute the profiles of H-alpha/H-beta and of the total IR (TIR)
to FUV ratio. Both data and model are used to estimate and compare the
extinction gradients at the FUV wavelength obtained from these various
indicators. We discuss the implications for the determination of the star
formation rate.

Astrophysics