The magnetic properties of 12 different types of aneurysm clip were investigated in order to identify which clips allow postoperative magnetic resonance (MR) imaging without risk. Clip-induced MR artifacts were also quantitatively studied using a geometrical phantom. Nonferromagnetic aneurysm clips like the Yaşargil Phynox, Sugita Elgiloy, and Vari-Angle McFadden clips do not appear to contraindicate MR studies performed with a FONAR beta-3000M imager. There is no clip movement upon introduction of the phantom into the MR imager, and the image artifacts caused by the clips are so limited that patients harboring such clips may well be considered for MR imaging. This examination may reveal information not obtainable by any other radiological modality.