The known distribution of tropical theileriosis is expanding rapidly and it may cover all the developing countries which have imported or intend to introduce exotic susceptible cattle into their possibly infected lands. Recently the disease has been confirmed for the first time in Nigeria and only last year in Pakistan, The disease is said to be prevalent in Ceylon and Afghanistan but the writer has not found any documented information to support this assumption. Tropical theileriosis has not been reported in the Arabian peninsula, which is surrounded by countries in which it is endemic even though it is the native land of the tick and many other species, in addition to having free or very loose livestock importation policies. This is particularly true in the Arabian Gulf Emirates namely Bahrain, Qatar and United Arab Emirates, where a person can easily import a carrier animal together with its ticks from any source. In my opinion the presence of T. annulata will be confirmed as soon as efficient veterinary services are established in these areas. It is clear that T, annulata is a fairly host-specific parasite and infects only domestic cattle, both Bos indicus and Bos taurus, and the Asian water buffalo (Bubalus bubalis). The Egyptian buffalo is more susceptible to tropical theileriosis than the Indian buffalo which seldom shows signs of the disease. Only latent infection is reported in adult Indian buffalo and even in splenectomized buffalo calves, only a few parasites are seen microscopically, even with intensive effort