Lead is a metal that has been implicated in toxic processes, which affect several organ systems in humans and other animals. The purpose of this study was to investigate the ultrastructural effects of lead on the brain of rats.Wistar Albino rats (180-200 g body weight) were divided into a controlled and lead acetate-exposed group. Rats received lead acetate at 500 ppm in their drinking water for 60 days. Both groups were fed with the same standard food, but lead acetate was added to the drinking water. During the experimental period, blood samples were drawn from the abdominal aorta of the anesthetised animals. At the end of exposure, body weight and blood lead levels were measured. The brain tissue samples were preapared and analysed by light and transmission electron microscopy. In the brain cortex, degeneration in some of the neuron cells, in the lumens of the blood vessels, dilation, hemorhagia and free floating erytrocytes were observed. Ultrastructural changes were revealed in the form of vacularisation of cell cytoplasm and degeneration in mitochondria, in the perinuclear cytoplasm, electron-dense inclusion bodies were detected, and dilation were in the endopasmic reticulum.