The range of metrical systems employed in the poetic traditions of Iranian languages is highly diverse. This is perhaps not surprising given the diversity of the phonological characteristics of the languages themselves and the varied contact histories they have gone through. It must be noted that the choice of metrical system, as shall be seen in this chapter in cases such as Kurdish, is only loosely determined by the phonological characteristics of the language, allowing for extralinguistic factors (e.g., musical tradition, social alignments, and historical incidents) to play an important role alongside linguistic ones. The aim of this chapter—by no means comprehensive in its coverage of Iranian languagesIranian languages—is to shed light on these metrical systems, their interactions, and the state of research in the analysis of the nature of these systems. In addition to the well-known quantitative metrical system used in various Iranian languages including Persian, as the rest of this chapter shows, syllabic and stress-based metrical systems have lived independently in traditions such as Kurdish and Pashto poetry. Given the near absence of scholarly work on metrical structure in certain other poetic traditions such as those of Ossetian and Yaghnobi, it is reasonable to assume that more diversity in metrical forms is going to be documented across Iranian languages in future decades. The first section in this chapter examines the quantitative metrical system of Persian poetry. This is followed by a discussion of closely related quantitative metrical systems such as those of Balochi and Kurdish. Finally, the last section discusses nonquantitative systems, most notably those of Gorani and Pashto.