Studies conducted in industrialized countries have shown that elderly demented subjects have increased risk of car accidents. However, there is no information about the effect of dementia on driving habits in non-industrialized countries. The number of motor vehicle crashes (MVC) and abnormal driving behaviours (ADB) (e.g. not recognizing traffic lights, driving in the middle of the road, etc.) were assessed with a semi-structured interview in 56 demented subjects and 31 elderly controls, all of whom were active drivers, at the Regional Registry of Dementia in Mendoza. Detailed neurological, psychiatric and neuropsychological examinations were also conducted on each subject. The presence of dementia and sex (male) predicted ADB, MVC and number of MVC (two or more). Among demented patients, ADB and MVC were associated with sex (male) and number of MVC was associated with sex (male) and Blessed Dementia Rating Scale for activities of daily living scores. Neither ADB, MCV, or number of MVC were associated with education level, or with cognitive or psychiatric measures. These findings showed that in developing countries, dementia has a significant contribution to MVC and ADB, as occurs in industrialized nations. Consequently, legislation to curb the risk of accidents caused by demented patients should be implemented. Furthermore, physicians must encourage demented patients (or their families) to discontinue driving, even those with mild dementia syndrome.