Crystals of optically active naphthidine and of binaphthyl are tetragonal,P41212 (orP43212),a = 7.945(1), 7.164(2),c = 24.264(5), 27.70(1) Å, respectively,Z = 4. The structures were solved by direct methods and refined by full-matrix least-squares techniques to respectiveR = 0.068 and 0.030 for 548 and 562 reflexions. The dihedral angles between the planes of the naphthalene residues are 87 and 102°, respectively. Bond lengths and angles are normal.