A disease resembling thiamine-responsive polioencephalomalacia of domestic ruminants is described in four wild pronghorn from Saskatchewan. One animal was found dead, two were recumbent and unable to rise and the fourth was staggering and ataxic. Lesions were confined to the brain and consisted of brain swelling with herniation, symmetrical hemorrhagic foci in the thalamus and brainstem, and laminar necrosis of cortical neurons. All animals had been eating grain prior to their death. Possible pathogenetic mechanisms including changes in rumen microflora resulting in thiamine deficiency, plant and salt intoxication are discussed.