The clinical, neuropsychological, and radiological features of a family, and the toxicological and neuropathological findings of one family member, who were acutely and severely intoxicated with methylmercury are reported after a 22-year follow-up from the Albuquerque Veterans Affairs Medical Center, the University of New Mexico School of Medicine, and the Environmental Health Sciences Center, the University of Rochester School of Medicine, NY. In 1969 a family in New Mexico had consumed pork containing methylmercury. Three children and a neonate developed severe neurological signs. At 22-year follow-up, the 2 oldest patients, ages 42 and 35 years, had cortical blindness, impaired stereognosis and graphesthesia, poor hand coordination, ataxia, choreoathetosis, dysarthria, and attentional deficits. MRIs showed loss of tissue in calcarine cortices, parietal lobes, and cerebellar folia. The 2 youngest were quadriplegic, blind, and mentally retarded and they died at ages 29 and 21 years. The brain of the patient poisoned at 8 years and dying at 29 showed cortical atrophy, neuronal loss and gliosis. Total mercury level in the occipital cortex was 1,974 ng/gm, 50 times that of a control; the Hg was mainly inorganic. Hair and systemic organs had Hg levels comparable to controls. [1]