Two haemoprotozoan parasites, Babesia caballi and Babesia equi, can cause equine piroplasmosis. Due to the presence of potential tick vectors in areas so far unaffected by equine babesias, import and export regulations often require the serum testing of animals for evidence of infection. Although the complement fixation test (CFT) has been recommended for detecting the presence of antibodies to Babesia spp., it has been demonstrated to have several disadvantages, including false-positive results and low sensitivity for detecting latent infections. An enzyme-linked immunosorbent assay (ELISA) may be an alternative for increased and sensitive detection of acute and latent babesial infections, but its development to date has been hindered by a limited antigen supply and poor specificity. In vitro cultivation of both parasite species and the identification of parasite proteins for diagnostic use has facilitated the development of a highly sensitive and specific ELISA. For the direct detection of the parasites, DNA probes are now available. Several drugs are available for the treatment of equine piroplasmosis. For instance, diminazene diaceturate is effective in the chemosterilization of B. caballi and in the elimination of clinical signs in B. equi infections. Antitheilericidal drugs such as buparvaquone have been demonstrated to be effective in combatting disease due to B. equi and may--in combination with imidocarb--also eliminate the parasite. The control of equine piroplasmosis must include effective tick control, seromonitoring of animals and the application of chemotherapy.