SUMMARYIn a prospective survey carried out over 9 months in 1984 in the Department of Bacteriology, Belfast City Hospital, Campylobacterjejuni* was isolated from 24 out of 1200 faecal specimens (2%) from patients with acute diarrhoea. This isolation rate is much lower than that from other parts of mainland Britain which report an isolation rate of between 8 and 15 %. It is difficult to explain this large discrepancy but the limited availability of unpasteurized milk and the generally worse summer here (fewer barbecues, picnics) may be some reasons to explain this low incidence in N. Ireland.