Results are presented on grain growth studies of the gamma titanium aluminide Ti-47Al-3Cr and Ti-48Al-2Nb-2Cr (at. %) alloys with nanocrystalline (initial grain size D-o < 100 nm) and microcrystalline (D-o similar to 1 mu m) structures. The alloys were produced by a hot isostatic pressing from gas-atomized and mechanically alloyed powders. The grain size distribution and mean grain size were determined after annealing at temperatures in the range of 725 degrees C to 1200 degrees C for annealing times of up to 800 hours using TEM. Grain size distributions normalized to the mean grain size were single-modal and time- and temperature- invariant both in the case of nano- and micro-crystalline materials. The grain growth was described by a single thermally activated rate process limited by a permanent pinning force.