A population study aimed at evaluating the influence of education on the prevalence of dementia was carried out in Ashkelon, a rural city in Israel. The whole population aged over 75 years was screened, with a very low refusal rate. Altogether, 1501 people were examined, using DSM III-R criteria for dementia. The prevalence of dementia increased with age and was higher among females and immigrants to Israel from Africa and Asia. The most significant correlation was with a low level of education, which completely explained the ethnic differences and partially the female predominance in the frequency of dementia. Our study confirms that schooling appears to be an important protective factor against the development of dementia.