Over 80 million doses of iodinated intravascular contrast media (CM) were administered in the most recent tabulations of 2003, corresponding to approximately 8 million liters, making it one of the highest volume medical drugs used compared to any other pharmaceutical. The evolution of CM has focused on minimizing adverse events by eliminating ionicity, increasing hydrophilicity, lowering osmolality and increasing the number of iodine atoms per molecule. Contrast media are classified into three general categories based on their osmolality relative to blood: high osmolar (5 times or greater than blood), low osmolar (2-3 times blood) and iso-osmolar (the same as blood). All imaging modalities that employ CM, especially computerized tomography (CT), have shown rapid growth. In the last two decades, the use of CT scanning has increased by 800%. From 1979 to 2002, the number of cardiac catheterization procedures in the USA increased by 390% and in Europe from 1992 to 1999 by 112%. There is a general consensus that renal insufficiency and diabetes are major risk factors for contrast-induced nephropathy (CIN), particularly when co-existing. The US Renal Data System documents a 'relentless' increase in kidney failure, projecting a 90% increase by 2010. Diabetes affects 194 million people worldwide and the number is anticipated to increase by 75% by 2025. The unavoidable conclusion is that patient exposure and prevalence of risk factors for CIN will continue to increase.