Extensive work has been carried out on the microstructural characteristics and property/microstructure relationships of two-phase TiAl alloys in the last decade. Based on these achievements, various engineering two-phase TiAl alloys have been developed and industries are seeking to accomplish their introduction for various structural components. This article reviews recent progress in understanding the deformation and fracture not only of such two-phase TiAl alloys but also single-phase TiAl. The single-phase TiAl is very brittle and exhibits mechanical properties which are considerably different from those of the TiAl phase in the two-phase alloys. However, clarifying the difference in mechanical properties between two-phase and single-phase TiAl alloys and its reasons is indispensable to deepen our understanding of the deformation mechanisms of the TiAl phase.