Active faulting in Iran is a direct indicator of active crustal deformation due to the convergence between Arabia and Eurasia which occurs at 2.1-2.5 cm/yr. In this paper active faults of Iran have been considered in some detail. Geometric characteristics, mechanisms and the trend of active fault zones in different areas of Iran have been discussed while considering their tectonic differences. Active faults in Zagros are blind and the focal mechanism solutions of the earthquakes of the region point to the presence of both thrust and transverse strikeslip faulting in its basement. Whereas in the rest of the country most active faults reach the surface. The earthquake mechanism solutions along active fault systems in eastern and central Iran imply dominance of strike-slip faulting in a transpression regime. Conversely, active faults in NW Iran are transtensive. The Alborz and Kopeh-Dagh fault zones are relatively vast active fault zones in which location of individual active faults is difficult. Aside from raised terraces in the shores of the Oman Sea, information on active faults in the Makran region is scarce.