Due to fragmentary and wide-ranging subjects in literary biographies, literary histories, bibliographies and other references, some subjects are mentioned which are not reliable in terms of authenticity. A case in point is the numerous works considered to be dah-nameh (Ten letters). Sometimes this situation arises as a result of the mistake made by some researchers who prejudge or blindly rely on the quotations without further investigation or reference to the original works. Theybelieved a minor similarity in name, lexical - and not terminological - reference, personal recollection and observance in a book to be a compelling reason for considering a literary work as belonging to a certain genre; in a way that 23 poems are recorded as dah-nameh, half of which are not truly of this type.The research questions in this paper are: What is investigated and reviewed based on theories related to literary genres? What criteria and tools are most useful for determining literary genres? Do all works called dah-nameh truly belong to this literary genre? At the end, by eliminating 11 works considered to be dah-nameh, only 12 of them remained. Seven poems fully meet the criteria for being classified as dahnameh. These poems include Manteq al-Oshshaq by Ohadi Maraghe’i, Mohabatnameh by Ibn Nasouh, Oshshaq-nameh by Ubeyd Zakani, Tohfat al-Oshshaq by Rokn Sa’en Semnani, Rouh al-Asheqin by Shah Shoja’, Rozat al-Mohebbin by Ibn Imad and Mahboub al-Qoloub by Hariri. There are another three works belonging to dah-nameh genre, including Oshshaq-nameh by Araqi, Sohbat-nameh by Hemam Tabrizi and Si-nameh by Amir Hussein Heravi. However, two works, including Rozat al-Asheqin by Aziz Bokhari and Eshrat-nameh, were left uninvestigated.