BACKGROUND: Little is known about the clinical importance of disease that is not presented to healthcare services. AIM: To determine the 5-year mortality among those with angina symptoms, known or not known by their general practitioner (GP) to have ischaemic heart disease (IHD). DESIGN: A prospective cohort study. SETTING: The study was conducted in the United Kingdom as part of the Royal College of General Practitioners' Oral Contraception Study. METHOD: In 1994-1995 women (n = 11,797) still under GP observation were sent a questionnaire that inquired about their smoking habits, other lifestyle issues, general health, and selected symptoms (including chest pain, assessed using the Rose angina questionnaire). The main outcome measure was the chances (odds) of dying during the next 5 years, among those with and without exertional chest pain, Rose angina or Rose myocardial infarction (MI), stratified by documented history of IHD. RESULTS: Overall, the lifetime prevalence of any exertional chest pain was 10.1% (95% confidence interval [CI] = 9.5 to 10.8); grade I Rose angina was 6.1% (95% CI = 5.6 to 6.6); grade II Rose angina was 1.3% (95% CI = 1.1 to 1.6); and Rose MI was 4.4% (95% CI = 4.0 to 4.9). The prevalence of each condition tended to increase with age, social class, parity, body mass index, and documented history of IHD. The proportion of women documented as having IHD was 23% among those with any exertional chest pain, 21.7% for grade I Rose angina, 37.7% for grade II Rose angina, and 31.4% for Rose MI. Compared to women without Rose angina, significantly higher odds ratios for all-cause mortality were observed among women with grade I Rose angina and no documented history of IHD (adjusted odds ratio [AOR] = 1.71, 95% CI = 1.05 to 2.79); those with grade II Rose angina and documented IHD (AOR = 3.94, 95% CI = 1.58 to 9.83); and women with grade II Rose angina and no documented history of IHD (AOR = 3.35, 95% CI = 1.47 to 7.62). CONCLUSIONS: Women with angina symptoms that have not been documented by their GP appear to have an increased risk of future mortality. Research is needed to determine the best way of identifying and managing these individuals.