Time‐resolved photoluminescence (PL) spectroscopy has been performed at 18 K on excitonic‐related emissions in an unintentionally doped hexagonal GaN epitaxial layer grown by two‐flow metalorganic chemical vapor deposition (TF‐MOCVD). Under low excitation condition, radiative recombination ofAfree exciton (EXA: 3.4921 eV) and neutral shallow‐acceptor bound exciton [(A0s,X): 3.4805 eV] dominated the spectrum. Decay time of (A0s,X) emission is relatively long (585 ps) indicating a small number of non‐radiative centers in the layer. At higher excitation densities, new PL peak appeared at 3.4864 eV and grew superlinearly with excitation densities. These features, combined with their transient behavior, suggest that this new emission band is due to the biexciton recombination. ©1996 American Institute of Physics.