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