This chapter describes the fundamentals of the ¹³C nuclear magnetic resonance (NMR) method and its operating techniques and outlines the results that are obtained to date for the vitamin B₆ group of compounds. NMR is the most powerful method to determine the structure, conformation, and dynamics of complex molecules. The chemical shift range of 13C—that is, the range over which different types of carbon can be detected—is much greater than for 1H. There is a similarity to 1H spectra in the relative positions of the resonances. Coupling between ¹³C and attached or nearby ¹H can lead to very complex spectra. Therefore, it is customary to remove these couplings by high-power irradiation over a range of frequencies sufficient to cover the entire 1H spectrum (broad band decoupling). The chapter also explains assignments of the ¹³C resonances of the parent B6 vitamins.