In the TEXTOR-94 tokamak, radial profiles of synchrotron radiation from relativistic runaway electrons have been measured. From these and measurements of the evolution of the radiation, a radial profile of the diffusion coefficient for the runaway electrons in the plasma core with MeV is derived. At half radius, is found. This result is compared with several other measurements of runaway diffusion coefficients derived mainly from runaway losses at the plasma edge.