Background British guidelines recommend treatment for mild hypertension at a cardiovascular (CVD) risk threshold of 20% over 10 years. However, treatment is targeted at the equivalent coronary (CHD) risk of 15% over 10 years. We examined the relationship between CHD and CVD risk in men and women with mild hypertension and assessed the accuracy of using a 10-year CHD risk threshold of 15% to identify patients at a 10-year CVD risk ≥20%. Design Cross-sectional survey of England in 1998. Methods We identified 5588 subjects aged 35-74 years free of cardiovascular disease with complete data for risk assessment. Of these, 1364 (24.4%) had mild hypertension (systolic pressure 140-159 mmHg or diastolic pressure 90-99 mmHg). The Framingham functions were used to estimate CHD and CVD event risk for each individual. Results At a 10-year CHD risk of 15%, the corresponding 10-year CVD risk for men and women, respectively was 20% and 21% in those aged <55 years, and 24% and 25% in those aged ≥55 years. Using a 10-year CHD risk threshold of 15% to identify patients at a 10-year CVD risk ≥20% had high specificity (>96%) in all four groups. For men and women respectively, the sensitivity was 73% (62-84%) and 62% (35-88%) in younger subjects, and 89% (85-93%) and 47% (38-56%) in older subjects. Conclusion Using a 10-year CHD risk of 15% to target patients at a 10-year CVD risk ≥20% was reasonably accurate for men but missed about 50% of women eligible for antihypertensive treatment. © 2002, European Society of Cardiology. All rights reserved.