Cardiac troponin measurements are routinely used for diagnosis and prediction of prognosis in patients presenting with an acute coronary syndrome.1–3 Newer high-sensitivity assay methods now allow detection of very low levels of serum cardiac troponin (hs-cTnl) but the clinical significance of these low troponin values in asymptomatic patients is unknown. In a cohort of 1135 asymptomatic adults without known atherosclerotic disease, Iribarren and colleagues examined the association between baseline hs-cTnl levels and coronary heart disease (CHD) events over a mean follow-up of 11.3 years (see page 1177). Low levels of troponin were detectable in all subjects (figure 1) and a baseline hs-cTnl >5.5 ng/L in men, >4.2 ng/L in women was associated with increased risk of subsequent CHD compared with the bottom quartile (HR 2.47, 95% CI 1.55 to 3.93), even after adjustment for age, sex, race, ethnicity, education level, diabetes, C-reactive protein, renal function and Framingham risk score. Overall, CHD risk category was re-classified in 18% of patients when hs-cTnl was added to the Framingham risk score.