BACKGROUND: Coronary bifurcations are prone to develop atherosclerotic plaque because there are turbulence of blood flow and high shear stress. True bifurcation lesion consists of significant obstruction of the main vessel and side branch, leading to more difficult and more complicated percutaneous coronary intervention (PCI). So, we intended to find out whether there are risk factors for true bifurcation lesion. METHODS AND RESULTS: Five hundred and ninty nine bifurcation lesions of five hundred and thirty nine patients were included. The lesions were classified into true bifurcation (n = 441) and false bifurcation (n = 158). We performed crosstabulation analysis between bifurcation type and clinical characteristics. Diabetes, hypertension, dyslipidemia and smoking did not revealed statistically significant frequency difference of two bifurcation type. However, obesity and chronic renal failure(CRF) frequency were significantly different in 2 types(p<0.05). Interestingly, obesity revealed relatively low frequency of true bifurcation. Again, the lesions were divided into 4 groups(quartile) according to BMI(body mass index : <18.5, 18.5��� <23, 23��� < 25, ���25 ) and CCr(creainine clearance : <30, 30��� <45, 45��� <60, ���60 ). True bifurcation lesions were significantly higher in the lowest quartile of BMI( 90.9%, 80.6%, 70.2%, 69.8%, P=0.014) and CCr( 86.4%, 84.3%, 76.8%, 69.2%, P=0.001). In a multivariate analysis, CRF and non-obesity were independent risk factors(P=0.025, 0.033, respectively). CONCLUSION: CRF and non-obesity are risk factors for true bifurcation lesion in coronary bifurcation. Furthermore, we need to investigate the mechanism in association with turbulence of blood flow and shear stress.