This study evaluated the mechanical properties and the surface elemental composition of Yasargil Phynox aneurysm clips implanted for 10 years in a patient with cerebral aneurysm. Two Yasargil Phynox aneurysm clips implanted 10 years previously to treat a ruptured vertebral artery aneurysm were retrieved when the regrown and ruptured aneurysm was repaired with a new aneurysm clip. Two new Yasargil aneurysm clips were used as controls. Measurements of closing force, bending strength, and the elemental composition of the clip surface were performed. The closing force of the retrieved clips was similar or greater compared to the force before implantation. The bending test showed that the elastic limit and 0.2% proof load of the retrieved clip were higher than those of the unused clip, whereas the ultimate load of the retrieved clip was similar to that of the unused clip. The elemental concentration of Cr oxide on the surface of the retrieved clips was almost the same as that on the unused clips. The present study demonstrated that Yasargil Phynox aneurysm clips retain their mechanical properties and surface elemental composition in vivo for a long time, which indicates that Yasargil aneurysm clips will remain reliable in patients for extended periods.