Bovine babesiosis is a tick-borne disease of cattle caused by the protozoan parasites of the genus . , and are considered by International health authorities (OIE) as the principal species of Babesia that cause bovine babesiosis. Animals that recover from a babesial primo infection may remain as persistent carriers with no clinical signs of disease and can be the source of infection for ticks that are able to acquire parasites from infected cattle and to transmit parasites to susceptible cattle. Several procedures that have been developed for parasite detection and diagnosis of this infectious carrier state constitute the basis for this review: A brief description of the direct microscopic detection of -infected erytrocytes; PCR-based diagnostic assays, which are very sensitive particularly in detecting in carrier cattle; in-vitro culture methods, used to demonstrate presence of carrier infections of sp.; animal inoculation, particularly for isolation are discussed. Alternatively, persistently infected animals can be tested for specific antibabesial antibodies by using indirect serological assays. Serological procedures are not necessarily consistent in identifying persistently infected animals and have the disadvantage of presenting with cross reactions between antibodies to sp.