The association of snoring with hypertension and ischaemic heart disease (IHD) was tested by postal questionnaire in a population of 3847 men and 3664 women aged 40-69 years. Hypertension associated highly significantly with snoring, the relative risk (RR) of hypertension between habitual snorers and never snorers being 1.94 in men and 3.19 in women. This association was also found when adjusting for body-mass index. A significant association between angina pectoris and habitual snoring was observed in men (RR = 2.22). In women the relative risk was not significant. An association between habitual snoring and angina pectoris in men was also found after adjusting for hypertension and body-mass index (RR = 2.01, p less than 0.01). The relative risks for myocardial infarction and hospital admission for IHD for habitual snorers were non-significant.