Germanium nanowires doped with manganese have been synthesized by thermal co-evaporation of Ge and Mn powders onto silicon oxide substrates with Au catalyst nanoparticles. Scanning electron microscopy images show a uniform and highly dense distribution of germanium nanowires with typical diameter and length of 40 nm and few tenths of micron respectively. Transmission electron microscopy and X-ray diffraction indicate that the nanowires are single crystals grown along the [100] axis. Energy dispersive X-ray results demonstrate the effectiveness of Mn doping of the nanowires.