Sharp-line emission near the absorption edge due to recombination of electrons and holes in recently available high-purity GaAs has been observed. At 4.2°K exciton emission is observed at 1.5143 0.0005 eV. The temperature dependence of this line is followed to 200°K and discussed. Below the energy gap a set of three lines is observed separated from each other by a longitudinal optical mode phonon energy (0.0364 0.0005 eV). In crystals grown in an O2 atmosphere an emission is observed apparently due to recombination of a bound exciton. The intensity of this line relative to the exciton line increases with O2 pressure and occurs 0.0015 eV below the exciton line. © 1963 The American Physical Society.