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SUMMARY – The pistachio tree (Pistacia vera L.) is a member of the Anacardiaceae family and originates in Central Asia. Two centres of diversity have been described for P. vera, an area from Iran into eastern Turkey and an area in northern Afghanistan and southern Turkmenistan. Pistachio is the only species in this genus, successfully grown in orchards, which produces edible nuts large enough to be commercially acceptable. Iranian species of P. vera is the subject of a chromosomal study. Frequently, meiosis in this species was regular and showed 15 bivalents at the first metaphase. Most bivalents had two terminal chiasmata. The mean number of chiasmata was estimated at 1.35 for each bivalent at the first metaphase. One to five pair