Abu Nasr al-Fârâbi (870-950 AD) is one of the prominent Muslim Philosopher. As a commentator of Aristotle he had gained eminent position and he came to be called ‘The second Teacher’. In this article I am going to deal with al-Fârâbî’s two important treatises which are called ‘‘Risâle fîmâyenbağî en yukaddeme kable te'allümi'l-felsefe (What Should Be Learnt Before Attempting Philosophy) and, el-Cem beyne ra’yeyi’l-hakîmeyn Eflâtûn el-İlâhî ve Aristûtâlis (Treaties of Agreement between the ideas of the two philosophers, the divine Plato and Aristotle) in respect to genuineness or spuriousness. During the Translation activities some treatise which belongs to Neo Platonist commentatorshad translated into Arabic partly or completely and signed with al-Fârâbî’s name. As an example of these treatises I choose firstly above mentioned ‘Risâle fîmâyenbağî’ andcompared with the text of Ammonius’ commentary on Aristotle’s Categories. As result I diagnosed that the prolegomena of this commentary is the same with this treatise and belongs to Neo Platonist commentator Ammonius. Secondly I’ve choosen so called ‘ el-Cembeyne ra’yeyi’l-hakîmeyn’ and examined carefully. At the end of this examination I realized that this treatise could not be belong to al-Fârâbî but might be written by his pupil Yahyaibn Adiy who is foremost translator of Greek and Syriac philosophical texts into Arabic.