Deep-level transient spectroscopy measurements were utilized to investigate deep-level defects in metal–organic chemical vapor deposition-grown, unintentionally doped p-type InGaAsN films lattice matched to GaAs. The as-grown material displayed a high concentration of deep levels distributed within the band gap, with a dominant hole trap at Ev+0.10 eV. Postgrowth annealing simplified the deep-level spectra, enabling the identification of three distinct hole traps at 0.10, 0.23, and 0.48 eV above the valence-band edge, with concentrations of 3.5×1014, 3.8×1014, and 8.2×1014 cm−3, respectively. A direct comparison between the as-grown and annealed spectra revealed the presence of an additional midgap hole trap, with a concentration of 4×1014 cm−3 in the as-grown material. The concentration of this trap is sharply reduced by annealing, which correlates with improved material quality and minority-carrier properties after annealing. Of the four hole traps detected, only the 0.48 eV level is not influenced by annealing, suggesting this level may be important for processed InGaAsN devices in the future. © 1999 American Institute of Physics.