We present results of pressure-dependent photoluminescence (PL) studies of single-crystalAlxGa1−xNepitaxial films grown on sapphire substrates by metalorganic chemical vapor deposition. PL measurements were performed under hydrostatic pressure using the diamond-anvil-cell technique. PL spectra taken from theAlxGa1−xNepitaxial films are dominated by strong near-band-edge luminescence emissions. The emission lines were found to shift linearly towards higher energy with increasing pressure. By examining the pressure dependence of the spectral features, the pressure coefficients for the PL emissions associated with the direct &Ggr; band gap ofAlxGa1−xNwere determined. Our results yield a pressure coefficient of4.0×10−3 eV/kbarforAl0.05Ga0.95Nand3.6×10−3 eV/kbarforAl0.35Ga0.65N.©1998 American Institute of Physics.