A case of simazine toxicosis in sheep was investigated. Affected animals exhibited generalized muscle tremors which progressed to mild tetany followed by collapse of the hind legs. Other signs included a short prancing gait with head tucked in a similar manner to that of a show pony. Death occurred within 2 to 3 d of the appearance of clinical signs. Mild to acute myocardial degeneration was evident; the livers had mild to acute hepatic fatty change. The levels of simazine found in livers varied from less than 0.2 mg/kg to almost 2 mg/kg in the worst affected animals.