We report the results of ab initio energy-band calculations for the ternary intermetallic compound GdMn₆Ge₆. The ferrimagnetic arrangement of Gd and Mn magnetic sublattices is reproduced as well as the average moment per Mn atom. The comparatively low strength of the Gd-Mn effective exchange coupling and the occurrence of a weak orbital polarization (3%) at the manganese sites are further results of this analysis. The numerical results are compared with prior magnetization and hyperfine-field analyses.