The role of ST2 in stable coronary artery disease (CAD) has not yet been well defined. This study was performed to investigate baseline serum soluble ST2 (sST2) level can predict clinical outcomes in patients with stable CAD. A total of 388 consecutive patients with suspected CAD (65 years and 63.7% male) in stable condition referred for elective invasive coronary angiography (ICA) was prospectively recruited. Major adverse cardiovascular event (MACE), including cardiac death, non-fatal myocardial infarction, coronary revascularization (90 days after ICA), and ischemic stroke during clinical follow-up was assessed. Most of the patients (88.0%) had significant CAD (stenosis ≥ 50%). During median follow-up of 834 days, there was 29 case of MACE (7.5%). The serum sST2 level was significantly higher in patients with MACE than those without (47.3 versus 30.6 ng/ml, P < 0.001). In multiple Cox regression model, higher sST2 level (≥ 26.8 ng/ml) was an independent predictor of MACE even after controlling potential confounders (hazard ratio, 13.7; 95% confidence interval 1.80-104.60; P = 0.011). The elevated level of baseline sST2 is associated with an increased risk of adverse clinical events in stable CAD patients. Studies with larger sample size are needed to confirm our findings.