Aim To investigate the gender differences of clinical characteristics and lesion morphology in patients with borderline coronary lesions. Methods From February 2007 to May 2009,1 920 patients from 4 first-class teaching hospital of BeiJINg with borderline coronary lesion (stenosis resulting in > 20% and < 70% lumen diameter reduction) confirmed by coronary angiography were enrolled consecutively. A total of 2 215 lesions were analyzed by Quantitative coronary angiography. Results A total of 639 female and 1 281 male were enrolled. Female patients were older than male subjects (65.47±8.60 years old vs 60.30±10.38 years old,P><0.01). The incidence of hypertension and diabetes was higher in female group (74.34% vs 60.50%,P><0.01; 26.45% vs 22.25%,P><0.05),but the incidence of smoking and history of myocardial infarction (MI) and PCI were lower in female group (6.42% vs 48.95%,4.39% vs 12.1%,12.21% vs 18.58%,P><0.01). Compared with male subjects,more female patients were diagnosed as coronary atherosclerosis (40.69% vs 28.81%,P><0.01) and less female patients were diagnosed as acute coronary syndrome (40.54% vs 50.67%,P><0.01). Calcification of lesions were more frequent in female cases (6.36% vs 4.14%,P><0.05) and plaque area was lower than male cases (7.62±3.22 mm2 vs 9.18±4.29 mm2,P><0.01). There was no signifi cant difference between genders with regard to other coronary lesion features. Conclusion Female patients with borderline coronary lesions were older than male subjects and had more concomitant diseases. However,female patients had less severe coronary lesions and higher incidence of calcification than male subjects.