The serological cross reactivity between the Malaysian Theileria and the other benign Theileria species from Japan and Australia, which are tentatively referred to as T. sergenti and T. buffeli respectively, was examined. A total of 290 serum samples from cattle were collected from 9 states (25-38 samples from each state) in Peninsular Malaysia and the ELISA was carried out to measure the specific optical density against T. sergenti and T. buffeli antigens. All the samples except two cattle, reacted more intensely to T. buffeli antigen as compared to T. sergenti antigen. Therefore, it is suggested that the Malaysian Theileria species of cattle bear a serological resemblance to T. buffeli, as compared to T. sergenti. In addition, the serological survey of bovine theileriosis in Peninsular Malaysia was also carried out. A higher reactivity to T. buffeli antigen in ELISA was generally observed in the serum samples collected from the various states. There were, however, a few exceptions which showed a lower reactivity to T. buffeli antigen in ELISA in samples from the two states in the east coast of Peninsular Malaysia.