Contrast-induced nephropathy is the third most common cause of acute renal failure in hospitalized patients. The purpose of this study was to compare three supportive treatments for prevention of contrast-induced nephropathy in high-risk patients undergoing coronary angiography. In this randomized clinical trial study, 150 patients with at least one risk factor, such as, congestive heart failure, history of diabetes mellitus, age>65 years or renal failure were randomly assigned to three equal groups: First group (Sodium (Na) bicarbonate infusion), second group [(N-Acetylcysteine (NAC)+Sodium Chloride (Nacl)], third group (Nacl). Angiography was performed with 350 mgI/mL of Iohexol (Omnipaque). Serum creatinine (Cr), blood blood urea nitrogen (BUN), and urine pH were measured at the start of angiography and 48 hours later. The three groups had no significant difference in demographic characteristics or other risk factors before intervention (P>0.05). Forty eight hours after exposure, the Cr level increased significantly in the Nacl group (P=0.039), while these changes were not significant in the other groups (P>0.05). The incidence of contrast-induced nephropathy was not statistically significant between all the groups (P=0.944). Although the Cr clearance had no statistically significant difference, it was lower in the NaCl group. Therefore, Na bicarbonate may be the treatment of choice in the prevention of contrast-induced nephropathy, because of less prescribed fluid volume and a lesser time required for infusion of the fluid.