With increasing age, diseases affecting the cognitive functions are more frequent. These diseases may increase the risk for fatal car crashes. We analyzed the frequency of neuropathological alterations characteristic of Alzheimer's disease (i.e. neuritic and diffuse plaques, and neurofibrillary tangles) in two association areas of the brain, parietal and frontal cerebral cortex, from 98 fatally injured aged drivers. In the age groups of 65-75 and over 75 years of age, 50% and 72% of the drivers, respectively, had neuritic plaques in either parietal and/or frontal cortex. In 14% of all killed drivers the number of neuritic plaques reached the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) age-related histologic score C, which indicates the diagnosis of Alzheimer's disease (AD), and an additional 33% had score B, which suggests the diagnosis of AD. Neuropathological AD changes were most common in the brains of drivers killed in single vehicle crashes, followed by multivehicle crashes at intersections and least common in multivehicle crashes elsewhere, but the differences did not reach statistical significance. In a great majority (80-85%) of cases the killed aged driver was the guilty party of the crash. The results imply, that incipient AD may contribute to fatal crashes of aged drivers, and therefore the forensic autopsy of these victims should include neuropathological examination.