The present paper attempts to study the similarities between Jami's Leili and Majnoon, Nezami' s Leili and Majnoon, and Amir Khosro Dehlavi's Majnoon and Leili. Having studied these similarities, the researches came to the conclusion that Jami's work was considerably influenced by Nezami's and Dehlavi' s. In addition to the similarities, the differences between these three works were also investigated in order to reveal the novel qualities of Jami's Leili and Majnoon in comparison to Nezami's and Dehlavi's works. In general, there are many similarities and differences between Jami's Leili and Majnoon, Nezami's Leili and Majnoon, and Dehlavi's Majnoon and Leili. Their basic similarity is that in all the three mathnavis, the first four chapters are classically designated for giving praise unto God, thanksgiving, the Ascension, and the reason for the specific organization of the work, respectively. Furthermore, in all of these works, Majnoon's name is Gheis who is from Bani Amer tribe, and is born in the Arabian territory; Leili is also from an Arabian tribe, however; the name of her tribe is not mentioned by the three poets.