Summary of Zoroastrians conversion to Bahai Faith in Iran

Up to that time [1882-83] no one from among the Zoroastrians [in Yazd] had accepted the Faith. Indeed, the Bahá'ís could not imagine that these people would embrace the Faith, because they were not involved in the early history and events associated with the Manifestations of God and were not included in any discussions concerning the Faith. (Quoted in Taherzadeh, Revelation 103 1)

According to Dastur Dhalla, the eminent Zoroastrian theologian, roughly 4000 Zoroastrians converted to the Bahá'í Faith in Iran, with an additional 1000 in India (cited in Dhalla, Dastur Dhalla 703). This conversion movement involved a significant portion of the educated merchant elite of the Zoroastrians in Yazd (Stiles, "Early Zoroastrian"), all of the Zoroastrians of Qazvin (Dhalla, Dastur Dhalla 726), and a significant number in Kashan and Tehran as well. The accuracy of all these figures, being based largely on the impressions of outside observers, is open to question. Neither the Bahá'ís nor the minorities from which the conversions were occurring kept membership records at this time.
During the Babí period there were few minority conversions. The only account I have found is the lone instance of a Zoroastrian who witnessed a Babí being beaten, stripped naked, and paraded through the streets. This persecution induced the Zoroastrian to examine the religion, and he soon became a Babí ('Abdu'l-Bahá, Traveller's 21).

When Mírza Abu'l-Fadl, the great Bahá'í scholar, was expelled from his position as a teacher in a religious school after it became known he was a Bahá'í in 1876, he was able to obtain employment from the Parsi agent Manakji Limji Hatari, who had been sent by the Zoroastrian community in India to assist the Zoroastrians of Iran. Mírza Abu'l-Fadl taught Persian literature to Zoroastrian children in Manakji's new school and served as Manakji's personal secretary. Some of the earliest Zoroastrian conversions to the Bahá'í Faith resulted from Mírza Abu'l-Fadl's association with the Zoroastrian community (Mihrabkhani, Sharh Ahval-i 19-23).