Auger electron spectroscopy (AES) has been used to study the surface composition and electronic structure of hot-pressed samples of boron carbide. The samples had bulk compositions of B/sub 9/C and B/sub 4/C. After removing oxygen and excess carbon contaminants from the surfaces of the samples by noble-ion sputtering the AES estimates of surface B/C ratios were close to those of the bulk for each sample. Using the Auger data as a probe of the valence band (VB) of the samples, the shapes of the B KVV and C KVV lines were not found to be dependent on the stoichiometry of the sample, indicating that the local chemical bonding, respectively, for B and for C does not change significantly in going from B/sub 9/C to B/sub 4/C. Comparisons of the Auger line shapes with site-specific projected VB density-of-states calculations for B/sub 13/C/sub 2/ by Armstrong et al. (Acta Crystallogr. Sect. B 39, 324 (1983)) indicated at least a limited agreement between theory and experiment in terms of the total VB bandwidth. The shapes of the Auger lines indicate that both s and p VB electrons take part in the Auger decays.