More than three decades ago, transition metal such as copper or zinc were postulated to be required for the ethylene perception. However, there was no direct evidence for this metal requirement until very recently. Two studies using Arabidopsis thaliana, one genetic and the other biochemical, have provided complementary evidence for the role of copper in ethylene perception, closing this argument. Additional evidence for the importance of the metal in the ethylene-signaling pathway came with the recent discovery that EIN2, a central signal transducer in the ethylene-signaling pathway, has significant homology to the Nramp divalent cation transporters. These studies suggest that metal metabolism may have a critical role not only in ethylene perception but also in ethylene signaling.