Clinical hepatitis, diagnosed as being caused by virus type A by tests for specific immunoglobulin M, has been reported from laboratories in England, Wales and Ireland since 1980. There were 25541 reports in the following 9 years, a yearly average of 2838. A 7-year cycle is suggested by peaks in the numbers of reports of 4502 in 1982 and 4167 in 1988 with a continuing rise in 1989. Contact with other cases of acute hepatitis was recorded for 3899 patients (15%) of which 2497 (64%) were in families, 258 (7%) were in schools, 94 (2%) were in institutions/hospitals, 197 (5%) were in the neighbourhood, while 140 (4%) were contacts at work or socially. A possible food source was recorded for 122 (3%) with shellfish being specified in 56 cases. Recent travel abroad was reported for 3692 patients (15%) of whom 3027 (82%) had visited areas of high prevalence for hepatitis A. About half of them had been to the Indian sub-continent, in strong contrast to visits abroad by the general population each year of which only 7% of the 22 million visits are to areas of high prevalence for hepatitis A. Association with the Indian sub-continent was particularly high for children.