The purpose of the present research is to study the whole repertory of the Iranian erudite music radif. It proposes a new classification of the modes of this music, considering that, during the modern era of Iranian music, there is the influence of Western music theory, as well as the influence of a distorted articulation between the theory and the practice of  Iranian erudite music which led to an arbitrary classification of the Iranian modes.

During their history, these very old systems, underwent major deterioration which occulted their initial coherence. As musician expert from Iran, we were confronted with considerable inconsistencies during our multiple attempts of total apprehension of the Iranian modal system ; the existing theoretical explanations could never completely satisfy our curiosity. In this thesis, we humbly sought to denounce the pretences. We engaged a scientific approach in order to try to highlight a simpler and more coherent classification. 

 Our position, between emic and etic, place our research in the center of a double exchange, by sharing the two approaches : Western and Iranian - what we call the “temporal division of the knowledge”. 

The originality of our research is that instead of accepting the heritage just as we received it, we tried to base our work on more structural and technical aspects, by borrowing methods from Simha Arom. Indeed, after questioning whether it was necessary to treat these Iranian music in the field exclusively ethnomusicology or rather musicology, it appeared obvious to us that our work, which above all directed towards the structural and technical aspects and use methods of analysis closer to those of musicology, positions rather in the field of musicology - ethnological dimension not being approached in this study. 

The first chapter approaches the historical aspect and the origin of radif, the methods of its transmission, and locates our research in the current scientific panorama.  

The second chapter is devoted to the definition of the terms and the concepts used in this music such as radif, dastgah (mode), goucheh (the melodies) and of the elements which compose them. The forms used and the existence of the quarter tone are also studied.

In the third chapter, we redefine certain terms and concepts such as the notes pivots, the intervals to be able to analyze the modal systems- the dastgah. 

In the fourth chapter, we analyze the dastgâh, the ambitus of the goucheh, the scales and the goucheh representative of each dastgah.

The results of our investigations and our research, in particular the nineteen extracted scales are presented in the fifth chapter.

In the final chapter, we approach the concept of rhythm (old and modern), its fundamental rules and also the correlation between the rhythm, poetry and the song.