Contrast Induced Nephropathy remains a controversial topic. The clinical relevance of changes in laboratory parameters has been challenged; some authors have even suggested that CIN simply reflects natural fluctuations. Other areas of controversy include the pathophysiology of CIN, effectiveness of prophylactic approaches and differences in nephrotoxicity between individual CM. The aim of this review is to summarize our understanding of laboratory findings and explore their relationship to contrast media toxicity. This article is protected by copyright. All rights reserved.