The prevalence of gallstones was studied in 11,840 consecutive autopsies from 1940 to 1975 in the University hospitals of Essen. The total prevalence was 20.7%: 13.1% for men and 33.7% for women. The male to female sex ratio is 1:2.6. The crude prevalence for three 12-year periods showed a significant increase from 8.2 to 15% in men and from 25.7 to 36.3% in women (p less than 0.001). A detailed analysis showed that this increase occurred only in the age groups over 60 and was the consequence of the fact that a greater proportion of women over 60 came to autopsy. The age- and sex-specific morbidity ratio was calculated to standardize the data. This demonstrated considerable fluctuations in 3-year periods since 1940. It can be concluded that no real increase in the prevalence of gallstones occurred in the last 30 years.