Ectoparasitic insects play a major role in veterinary medicine. Fleas infest man and animals and are the most frequent external parasites of companion animals worldwide. Some species are known to be vectors of zoonotic pathogens. Dogs and cats may play an important role either as reservoir of some of the pathogens or as transport vehicles for infected eas between their natural reservoirs and human beings, thus playing a crucial step in the transmission cycle of ea-borne diseases. This article reviews relevant literature on morphology, classi cation, host speci city, geographical distribution, and seasonality of eas infesting dogs and cats in order to improve their timely identi cation, prevention, and control.