This paper focuses on the review of risk factors of Alzheimer's disease (AD). Despite the vast literature on AD only advanced age and genetic predisposition have been known factors in the development of this disease. Recent data estimate a point prevalence of 3% in the age group from 65-69 and a steady increase to 24% after the age of 85 and older. The allele ApoE4 on chromosome 19 is liked to the sporadic form of AD with late onset, although not disease-specific. The risk factor is increasing from 20 to 90% with the growing number of ApoE4-allele. Since the sporadic form of AD is diagnosed much more frequently and about 40% of the cases are ApoE4-negative, one should not overestimate the percentage of AD in patients with a genetic component. No gender differences have been established in view of education, social factors and higher life expectancy of women. Mental and physical activities seem to improve coping strategies and develop reserve capacities. The lack of education presents a risk factor as opposed to at least 6 years of elementary schooling. Various studies report an association of AD with head injuries. Depression, which is diagnosed 3 times more often prior to the onset of AD, may be part of a prodromal stage preceding the actual symptoms by several years. Thus, conclusions should be drawn with caution. No increased risk with nicotine and alcohol has been found. However, maternal age, exposure to aluminum, estrogen deficiency and various diseases have been controversially discussed.