A prospective study of the prevalence of gail stone disease at necropsy in a stable population has been undertaken over a 10 year period up to June 1988. In women, the prevalence of gail stone disease remained static but in men aged 50-59 years it rose from 7% (n= 148) in the first three years to 18% (n= 138) in the last three years (p<001) and in men aged 60-69 it rose from 12% (n=370) to 20% (n=366, p<001). In the latter age group the female: male ratio fell from 2:1 to 0.8:1. The proportion of deaths from coronary heart disease in men fell slightly in those over 70 during the study period. There was a fall in deaths from coronary heart disease in all age groups in women. Men with gall stones were less likely to have had a cholecystectomy than women, and overall 88% of gall stones remained in situ. In a parallel clinical study, the number of cholecystectomies carried out in the same district fell by 18% over the 10 years without any apparent change in the provision of resources. Cholecystectomy remained almost three times more frequent in women. National data indicate that there have been major changes in the average diet before and during the period of study in favour of reducing coronary heart disease. There has been no change in mortality fronm coronary heart disease in young men but if the observed increase in the prevalence of gall stones in men and the decrease in deaths from coronary heart disease in women are real phenomena, it seems likely that they are diet related. In 1978, a prospective necropsy and clinical study of gall stone disease was undertaken to look for evidence of change in the prevalence, operation rates, and morbidity of gall stone disease over a period of time in a single health district. The preliminary findings were published after the first two years' but a further evaluation of the necropsy data has been undertaken after 10 years of the study. An increase in the prevalence of gall stones in men, which was not found in women, was an unexpected finding but two recent studies have reported an unusually high proportion of gall stones in older men.2 3 There are many necropsy studies of gall stone prevalence4 but few have recorded a female to male ratio of much less than the expected 2: 1,'-8 and two of these were oriental studies in which subjects had a high proportion ofpigment stones. There have been several studies of the prevalence of gall stones over time,9' all ofwhich showed an increase, although the Danish studies have shown a subsequent fall since the 1960s. " I3 Bateson and Bouchier'4 did not find any evidence of a real increase in Dundee from the turn of the century to 1973 but there was an increase from 1974-83,'5 and Brett and Barker, in an extensive review of the published reports,4 found that the mean prevalence of gall stones in European countries rose from 10-5% before 1940 to 18 5% afterwards. These studies were not age adjusted, however, and Balzer et al'6 found that the prevalence of gall stones in Essen apparently increased from 8 2% to 15% in men and from...