BACKGROUND In childhood coeliac disease highly varying incidence rates have recently been disclosed. Very low incidence rates (0.09/1000) were found in Denmark, in contrast to our neighbouring country Sweden (2.93/1000). Whether this was accounted for by the diagnosis being delayed until adult life was unknown. No studies concerning the epidemiology of adult coeliac disease in Denmark have been published so far. METHODS The annual incidence rates of adult coeliac disease were determined in the county of Copenhagen during the years 1976-91. The risk of having developed coeliac disease in adult life, on the basis of age and sex, was calculated. The life time prevalences by 5-year birth cohorts were calculated. RESULTS The overall incidence had been stable during the period and was 1.27/10(5). The figures for females and males were 1.55/10(5) and 0.96/10(5), respectively (p = 0.04). The median (range) age at the time of diagnosis was 40.1 (16-81) years. Age-specific incidence rates varied considerably, with the peak rate located in the middle-aged population. Low incidence rates were demonstrated in teenagers and young adults, and increasing rates was seen again in old age. The incidence rates were influenced by age at diagnosis (p = 0.01) and sex (p = 0.04) but not by the year when diagnosed. For a subject aged 89 years the risk was 0.88/1000. The corresponding figures for males and females, were 0.75/1000 and 1.0/1000, respectively. The overall prevalence was 45.9/10(5); males and females, 35.3/10(5) and 55.8/410(5), respectively. CONCLUSIONS This incidence/prevalence is one of the lowest reported and is definitely lower than prevalences reported in our neighbouring Scandinavian countries. Nothing points to higher incidence rates being present in Danish adults to compensate for the previously demonstrated very low rates in Danish children.