Time‐resolved photoluminescence spectroscopy has been used to probe the dynamics of optical transitions in GaN epitaxial layers grown by molecular beam epitaxy. In particular, systematic measurements on a band‐edge transition at about 3.42 eV have been carried out. Recombination lifetimes of this transition have been measured at different emission energies. Our results clearly show that the time‐resolved photoluminescence can provide immense value in the understanding of the dynamic processes of optical transitions in GaN. ©1995 American Institute of Physics.