Far-infrared absorption due to Lyman transitions of the Be acceptor in GaAs has been measured in bulk molecular-beam-epitaxy-grown samples at various temperatures and under different illumination conditions. Sharp lines of energy at 1.9 K of 134.420.06, 166.760.05, and 182.300.05 cm1 are observed, being the G, D, and C lines, respectively. Fiorentini’s recent calculation Phys. Rev. B 51, 10 161 1995 of the acceptor energy spectrum in GaAs is in good agreement with these results. At 1.9 K the G, D, and C linewidths are 1.060.14, 1.160.04, and 1.860.05 cm1, respectively, and the integrated intensities are in the ratio 11.55.6:100:57.69.8. External illumination during cooling or measurement had no effect on the observed spectra.