Callistemon is an important genus in the family Myrtaceae which contains about 34 species. The members of this genus are known for their ornamental potentials, in addition to their outstanding value in conventional medicine in many parts of the world. Updated chemical analysis of the Callistemon genus has provided a variety of essential phytocompounds belonging to different chemical classes including terpenes, phenolic derivatives, flavonoids, anthocyanins, neolignans, phloroglucinol derivatives and other miscellaneous compounds. Hence, this dissertation reflects a systematic evaluation of the Callistemon genus phytochemical and biological studies, in addition to a summary of the previous studies’ results as well as an overview of the possible directions of Callistemon species study