Synthetic bilayer membranes are two-dimensional arrays of am-phiphilic molecules. A large number of bilayer-forming am-phiphiles are designed by combinations of the structural elements (hydrophilic head, hydrophobic tail, connector, rigid segment, etc.). Metal chelate units have been incorporated into bilayer membranes as part of the bilayer component or as guest molecules. In the former example, a positively charged Cu(II)/polyamine complex and a Cu(II)/diketone unit are used as the hydrophilic head and rigid segment, respectively. The anisotropic orientation of these Cu(II) chelates is confirmed on the basis of the anisotropic ESR patterns observed for cast films of aqueous bilayer dispersions. Anionic planar Cu(II) complexes are incorporated noncovalently into cast films of ammonium bilayer membranes. These Cu(II) complexes are placed either horizontally or vertically, depending on the distribution of negative charges within each molecule. Strong antiferromagnetic interaction is observed when Cu(II) chelates are arranged two-dimensionally on bilayer membranes.