INTRODUCTION: Lung cancer is the leading cause of cancer deaths in many Western countries, but its incidence has never been studied in Northern Ireland.

AIMS: Accordingly, the present study was mounted to determine, for the first time, the incidence of the condition in Northern Ireland and to compare the findings with other regions in the British Isles.

METHODS: A notification study of the incidence of lung cancer (ICD 162) was conducted in Northern Ireland during 1991/1992. Notifications from 6 sources were computerised and linked. Incident cases were identified and analysed in relation to Age, Sex and Geographical region-Northern Ireland, England and Wales, Scotland and the Republic of Ireland.

RESULTS: Some 900 incident cases of lung cancer were identified. The incidence rate per 100,000 population was found to be 57.04. Mortality underestimated incidence by 12.5%. ([Formula: see text]). The male to female incidence ratio was 2.1: 1, and this ratio was similar in other regions, except Scotland, where the ratio was 1.7:1. The null hypothesis of a common incidence distribution across regions was formally rejected. A variety of models were fitted and a model in which the log-odds on incidence was a quadratic function of age fitted most of the regional data.

CONCLUSIONS: Northern Ireland had the lowest incidence of lung cancer in the UK, but its overall rate was still 40% higher than that observed in the Republic of Ireland which had the lowest rate in the British Isles. Across regions, the pattern of incidence by age and sex was complicated, but a linear logistic model fitted all of the Irish data and the female data in Scotland, satisfactorily.