e compared the therapeutic effect of three anticoccidial drugs (toltrazuril, sulphadimidine andamprolium) in buffalo (Bubalus bubalis) calves experimentally infected withEimeria bovis(E. bovis)andE. zuerniioocysts (3104 oocyst/calf). Buffalo calves (1.5–4 month old, 70-kg body weight) wererandomly allocated into 3 groups (9 calves each). Group T was experimentally infected with oocysts andtreated with toltrazuril (20 mg/kg BW twice orally at a 1-week interval). Group S was experimentallyinfected with oocysts and treated with sulphadimidine (125 mg/kg injected IM followed by half dose for 4successive days). Group A was experimentally infected with oocysts and treated with amprolium (50 mg/kgorally for 7 successive days). Each group had three subgroups (three calves/subgroup) to represent timing ofthe drug administration: 1st day of coccidia infection (FD), onset of clinical signs of coccidiosis (CC), andonset of oocyst shedding into the faeces (OS). Clinical signs, body-weight gain (BWG) and number ofoocysts per gram feces (OPG) were monitored daily for 35 days post-infection (DPI). The OPG werereduced (but the BWG was not different) in the T calves compared to S and A calves. Within the same group,treatment from the 1st day of infection reduced the OPG and increased the BWG compared to the latertreatment timings