Objective To investigate the relationship of plasma leptin concentration with occurrence of major adverse cardiac e-vent in patients with ST-segment elevation AMI during the hospitalization. Methods Venous blood of 80 patients and 40 healthy subjects were collected. Plasma leptin concentration was determined. Statistical analysis was undergone. Results Major adverse cardiac event occurred in 22 (27.5% ) cases. Plasma leptin level showed obviously higher in the patients than that of healthy subjects(P < 0.01). Plasma leptin level was a risk factor of occurrence of major adverse cardiac event (P<0.01) and predicted of happening with marked clinical value( P < 0.01). Conclusion Plasma leptin concentration is enhanced in patients with ST-segment elevation acute myocardial infarction, and its determination can help to judge the occurrence of major adverse cardiac event during the hospitalization.