The association between gadolinium (Gd)-containing MR imaging contrast agents and the development of nephrogenic systemic fibrosis (NSF) is well recognized. The authors review the histopathologic features, methodology, and results of analysis of tissues for Gd in NSF. Scanning electron microscopy/energy dispersive x ray spectroscopy (SEM/EDS) provides sensitive detection of individual Gd-containing deposits in situ. Secondary ion mass spectroscopy has far greater sensitivity for detection of Gd than SEM/EDS and allows correlation at the cellular level. Inductively coupled plasma mass spectrometry is the recognized method for full quantitative analysis of Gd in tissues but requires destruction of the tissue and does not allow spatial correlation. In practice, the different analytic techniques provide complementary data and can be selected based on the information required.