Nitroxinil is an anthelmintic drug mainly used for the control of liver fluke in sheep and cattle. Nitroxinil is active against the liver fluke the Fasciola hepatica and to a lesser extent against thread worms in the gastrointestinal tract. The efficacy of nitroxinil administered once by subcutaneous injection at a dosage regimen of 20 mg/kg live mass was evaluated against natural infestations of parafilaria bovicola in cattle. Trial animals were slaughtered 14 weeks after treatment. Treatment reduced the number of bleeding points by 97,8%, eosinophil-positive carcass lesions by 85,7% and eosinophil-positive lesion area by 92,8%, compared with controls.