Lead encephalopathy will be induced in suckling rats by feeding the toxin to the mother. When neurologic symptoms have developed, the following modes of therapy will be tested: intraperitoneal hypertonic urea, steroids, chelating agents, and supplemental vitamins. The effect of treatment on cerebral edema will be determined by measuring brain water, electrolytes, and uptake of I131 labeled serum albumin. Lead encephalopathy will also be induced by the oral administration of lead and vitamin D to juvenile rhesu monkeys 4 to 6 months of age. During the experimental period, the animals will be trained to discriminate form and color. Their motor activity will be trained to discriminate form and color. Their motor activity will lso be perodically monitored by an electronic device. Suriving animals will be killed. The brains of all monkeys will be studied by routine histological methods will special emphasis on the cortical distribution of the lesions. Blood lead levels will be periodically determined during life and at postmortem bone levels will be measured.