Nephrogenic systemic fibrosis (NSF) is a disabling and potentially fatal disease that has been associated with gadolinium-based contrast (GBC) agents. There are five GBC agents approved for use in the United States and another four approved in Europe. The proposed cause of NSF is release of free Gd3+ into tissues in patients with decreased renal function. The number of associated cases and the potential to release free gadolinium is not equal between these agents. Gadodiamide has the largest number of reported cases of NSF followed by gadopentetate dimeglumine and gadoversetamide. The market share of these agents may contribute to the number of reported cases. The pharmokinetics of gadodiamide and gadoversetamide indicate that these two agents are more likely to release free Gd3+ than other GBC agents. Gadoteridol and gadoterate meglumine have a cyclic structure, making them less likely to release free Gd3+, and there is only a single reported case of NSF associated with gadoteridol use alone. Further research into individual agents is needed.