Background and Aims: Unfractionated heparin (UFH) and bivalirudin are widely used as anticoagulants in cardiovas-cular medicine, including for thrombosis prevention during coronary angiography (CAG) and percutaneous coronary in-tervention (PCI). Little is known of the effects of UFH and bivalirudin on liver and kidney function in patients subjected to these procedures. This study compared the effects of bi-valirudin and UFH on liver/renal function in patients with coronary artery disease who underwent CAG, with or with-out PCI. Methods: The study comprised 134 consecutive patients (40–89 years-old), who underwent CAG (or CAG and PCI); among them, 66 and 68 patients were subject to, respectively, bivalirudin or UFH. The following indicators of liver/renal function were measured before and after the pro-cedures: plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen, estimated glomerular filtration rate (eGFR), creatinine clearance, and serum creatinine. Patients were further stratified by sever-ity of chronic kidney disease (CKD), based on original eGFR. Results: Relative to baseline, in the bivalirudin group, ALT and AST were higher after CAG (p=0.005, 0.025), while blood urea nitrogen and serum creatinine were lower (p=0.049, <0.001). In the UFH group, ALT, AST, eGFR, and creatinine clearance were lower after CAG (p≤0.001, all). Patients given bivalirudin with moderate or severe CKD, but not those with mild CKD, gained significant improvement in kidney function. Conclusions: Relative to UFH, bivalirudin may better safeguard the renal function of patients with coronary artery disease who undergo CAG, especially pa-tients with moderate-to-severe renal insufficiency. UFH may cause less liver damage than bivalirudin.