The present study is a comprehensive taxonomic revision of the genus Bromus (Poaceae) in Iran. Based on the examination of 1500 herbarium specimens from Iran, 285 from neighboring countries and 30 type specimens, some nomenclatural modifications and classification changes are made. The tribe Bromeae for Iran was previously recognized as including the genera Bromus (29 species) and Boissiera (one species). Here, the number Bromus species in Iran is increased to 45. The Iranian taxa of the tribe Bromeae comprise the genus Bromus with 6 sections, 39 species and 40 taxa (two subspecies), including the cultivated B. catharticus, B. inermis and B. pumilio (synonym Boissiera squarrosa). Bromus rechingeri, B. pseudojaponicus and Bromopsis gabrielianae are reduced to synonymy. An identification key and detailed information of the geographical distribution of all treated species is provided.