It is unclear whether N-acetylcysteine is useful in preventing contrast-induced nephropathy in patients undergoing coronary angiography. Because of different inclusion and exclusion criteria and different definitions of studied parameters, various studies have reported different outcomes. A systematic search was done using PubMed, Ovid, and the Cochrane library, and studies were pooled after strict inclusion and exclusion criteria. Separate analysis was conducted for all endpoints including only studies that used an N-acetylcysteine (NAC) dose of 600 mg, and another separate analysis was conducted for all endpoints including only studies that used oral route NAC to study how the dose and route of administration of NAC affect the outcomes. The results of the pooled analysis significantly favored the use of NAC to prevent contrast-induced nephropathy in patients undergoing coronary angiography but failed to show any significant benefit in terms of creatinine levels preangiography and postangiography, need for dialysis, and all-cause mortality. The effects of route and dose of NAC did not show any significant difference except in respect to incidence of postcatheterization nephropathy. This study shows that NAC may not have any impact on clinical outcomes after peripheral or coronary artery catheterization and that dose and route do not seem to have any effect on these outcomes.