[en] Purpose. To determine the role of prophylactic N-acetylcysteine in the prevention of contrast-induced nephrotoxicity. Methods. One hundred and sixteen patients undergoing noncoronary angiography, with or without pre-existing renal impairment, were randomly assigned to receive prophylactic oral N-acetylcysteine or no treatment. Serum creatinine (sCr) was measured prior to angiography and 48 hr after the procedure. Urine samples were collected before and after the examination for measurement of malondialdehyde (MDA) concentration. Contrast-induced nephrotoxicity (CIN) was defined as a rise in serum creatinine of 0.5 mg/dl (44 mmol/l) at 48 hr. Results. Complete data were available on 106 patients, 53 of whom had received N-acetylcysteine. There were no significant differences between the two groups in baseline characteristics, type of angiogram, or volume and concentration of contrast used. Three patients (2.8%), all of whom had received N-acetylcysteine, developed CIN. In the N-acetylcysteine group, the mean serum creatinine in patients with renal impairment was 151.0 ± 44.2 μmol/l prior to the procedure and 155.6 ± 48.6 μmol/l (p = 0.49) after the procedure. Respective values for those without renal impairment were 79.6 ± 15.1 μmol/l and 81.2 ± 20.0 μmol/l (p = 0.65). In the group that had not received N-acetylcysteine, the mean serum creatinine levels before and after the procedure were 150.0 ± 58.1 and 141.4 ± 48.0 μmol/l (p = 0.17) in patients with renal impairment and 79.7 ± 14.2 and 81.4 ± 15.4 μmol/l (p = 0.34) in those without renal impairment. In both groups, no significant change in urinary MDA concentration was observed. Conclusion. There is no benefit to the prophylactic administration of N-acetylcysteine in patients undergoing peripheral angiography using current contrast media