Iran Air has taken delivery of its first four ATR 72-600 turboprops.
Earlier this year, the carrier finalised a deal spanning 20 firm ATR 72-600s plus options on another 20.
The remaining 16 firmly ordered aircraft will be delivered by the end of 2018, says ATR.
Iran Air chief executive Farhad Parvaresh states that the turboprop fleet "showcases our will to provide newest-generation aircraft to our customers".
Following a relaxation of international sanctions against Iran over the last years, the country's flag carrier initiated a fleet modernisation programme that has also included commitments for 180 jets from Airbus and Boeing.
ATR chief executive Christian Scherer comments: "There are still historical moments in aviation, and this is one of them."