The secondary structures of Cd5Zn2MT-II and Zn7MT-II from rabbit liver and their derivative Pt7MT-II in solid state were investigated by Fourier transform is spectroscopy. The Cd5Zn2MT-II contains about 30% turns and half turns, 17% 310-helix, 4% unordered and 9% β-extended chain, which is similar to the content determined by the nmr analysis and is similar to the structures of the Pt7MT-II and Zn7MT-II. The results indicate that there is no evident conformation changes of MTs' secondary structure when the tetrahedral Zn and Cd ions of native MTs are replaced by square-planar Pt ion.