GaN nanotubular nanostructures have been synthesized by Au-catalyzed metallorganic chemical vapor deposition. GaN nanotubes with or without Ga-filled cores were observed. At 450°C, the amorphous Ga-N nanowire growth rate was controlled by the condensation at the liquid-solid interface. On the other hand, as the growth process became diffusion limited at 600°C with the rate of condensation surpassing the diffusion rate of N atoms, a tubular GaN structure partially filled by the Ga the column was formed. The nanotubes were characterized to be of single crystalline wurtzite phase. The growth was found to follow the vapor-liquid-solid mechanism. The fabrication method represents a new synthesis route for the one-dimensional complex building block in optoelectronics and biochemical sensing applications.