A cross-sectional study of gallstone disease, ascertained by ultrasonography, comprised 4581 men and women of Danish origin, aged 30, 40, 50, and 60 years, of whom 3608 (79%) took part in the investigation. The prevalence was assessed in relation to alcohol intake and number of daily meals. A randomly chosen subgroup of 593 persons was interviewed about their dietary habits. Both in the univariate and the multivariate analysis, gallstone disease was significantly related to abstinence from alcohol but not to number of meals. There was a trend towards positive association between gallstones and intake of refined sugars and total fat, whereas a negative trend was found between gallstones and intake of fibres and polyunsaturated to saturated fat ratio. None of the associations were significant. The same relations were observed when gallstones less than 10 mm were used in the analysis. The problem of assessing diet in relation to gallstone prevalence is stressed.