Background: Significance of an ST-T abnormality in subjects with no apparent heart diseases is to be determined. Subjects and methods: The study involved 44,990 adults (16,368 males and 28,622 females) aged 40-85 years who under went an annual health examination. Cardiovascular risks (CVRs) were considered positive if 1) body mass index was ≥ 25Kg/m2, 2) systolic blood pressure (BP) ≥ 130 mmHg and/or diastolic BP ≥ 85mmHg, 3) triglyceride ≥ 150 mg/ dl, 4) HDL-C level ≤ 40mg/dl for men and ≤ 50mg/dl for women, or 5) fasting blood glucose ≤ 110 mg/dl. The relation between CVRs and ST-T abnormalities were evaluated. Results: ST-T abnormalities were found in 6.49% in males, and more frequently in females: 8.45%. Each CVR and the number of combined CVRs were risk factors for ST-T abnormalities on ECG (P < 0.0001 for a trend). On the other hand, ECG-based LVH was found in 5.7% but showed no relation with CVRs or their com binations. ST-T abnormalities may represent preclinical cardiac involvement of CVRs more sensitively than LVH on ECG and ECG findings may be used in mass examinations. Conclusions: ST-T abnormalities without apparent heart diseas may be considered to be nonspecific but this cross-sectional study showed that they are related to CVRs and may be used as an early marker of preclinical cardiac damage by CVRs.