Recent studies have linked elevated serum sFas levels to atherosclerotic disease among patients. Confirming an association between obesity and serum sFas levels in healthy subjects would facilitate our understanding of obesity and its related disorders. We therefore analyzed serum sFas levels of 8,541 subjects selected as controls for a nested case-control study within the JACC Study. Body mass index (BMI) was calculated as the indicator of obesity based on self-reported height and weight. We found a statistically significant positive association between serum sFas levels and BMI among our apparently healthy subjects. Our result suggests that serum sFas rises to down-regulate increased apoptosis in atherogenesis processes caused by obesity.