The microstructural evolution produced during superplastic deformation of a fine grained gamma-TiAl alloy has been studied. Electron microscopy observations confirmed that at temperatures of 700-800degreesC extensive deformation occurred by twinning such that the twin interfaces produced a subdivision of the grains leading to a microstructural refinement through a subsequent recovery/recrystallization process. The initial spacing between mechanical twins decreases with decreasing deformation temperature and increasing strain. After large strains (60-70%) at those temperatures a refinement of the microstructures is observed such that the initial grains sizes become 100-150 nm at 700degreesC and about 300-350 nm at 800degreesC.