Introduction. Contrast-induced-nephropathy (CIN) is a common complication during angiography that may lead to long-term complications. This study was conducted to investigate the effect of melatonin administration on prevention of CIN in patients who underwent coronary angiography with intra-arterial contrast agents. Method. This is single-blind randomized clinical trial that was performed over 100 patients with indication for coronary angiography. Patients are randomly assigned to two equal groups. All patients in the 12 hours before and 12 hours after the procedure, were received adequate intravenous hydration with normal saline and for the intervention group in addition to hydration, the day before angiography and immediately after angiography 3 mg melatonin was administered. For all patients, serum level of creatinine (Cr), blood urea nitrogen (BUN) and glomerular filtration rate (GFR) before and 48 hours after the procedure were measured. Data were analyzed using SPSS 18 software. Results. Totally 100 participants with the mean age of 64.0±8.2 years were enrolled (63% male). There was no significant difference between intervention and control groups in baseline and demographic characteristics (P> 0.05). Although the mean serum Cr and BUN level increased in both groups, but the mean Cr, BUN and GFR before and after coronary angiography was not statistically significant. Based on the definition of CIN in the current study, 3(6%) patients from intervention group and 2(4%) patients from control group were affected by CIN (P = 0.243). Conclusion. It is likely that, melatonin administration has no significant effect on prevention of CIN following coronary angiography.