Chlamydia are the obligatory intracellular bacteria having unique biphasic life cycle. Chlamydia are known to infect through mucous membranes. The bacterium is Gram negative, coccoid belonging to family Chlamydiaceae and order Chlamydiales. Chlamydiaceae has the single genus Chlamydia; earlier on the basis of 16S and 23S rRNA sequences, two genera Chlamydia and Chlamydophila were proposed which was not adopted by Chlamydia research committee. Consequently in 2010, the International Committee on the Systematics of Prokaryotes adopted the single genus Chlamydia. Chlamydia has 12 recognized species which infect different host species. Among these species, Chlamydia trachomatis and Chlamydia pneumoniae are the human pathogens, while the rest of species infect various domestic and wild animals. Among these species, Chlamydia psittaci and Chlamydia abortus are the recognized zoonotic pathogens and have been discussed ahead. Other lesser known zoonotic chlamydial species infections have been dealt with at the end of the chapter.