Surface-Enhanced Raman Scattering (SERS) spectra of bilirubin-metal ion (Cu2+, Co2+, Zn2+, Cd2+) complexes (MBR) are reported. These spectra reveal significant differences between MBR and bilirubin (BR) itself. But SERS spectra of bilirubin-Cu2+, Co2+, Zn2+, Cd2+ complexes are similar to each other. The mole ratio of bilirubin-metal in the complexes M2+ : BR = 1 : 1 was measured. Empirical assignments of the major SERS bands are given. The spectrum of CuBR in solution is consistent with a square planar structure. It should be noted, however, that H 2 0 or COOH of another BR molecule occupy the positions above and below the plane in solutions of complexes of this type and forms Cu -0 bond.By comparing the SERS spectra of bilirubin-copper (or zinc) and biliverdin-copper (or zinc) complexes, the similar Raman frequencies and relative intensities were attributed to the oxidation of the bilirubin-copper (or zinc) complex to the green biliverdin-copper (Zn) complexes. It is shown that M2