Single crystals of two crystatalline forms, α and γ, in nylon 12 were obtained from dilute solutions. The single crystals of γ-form from diols solutions are ribbon like lamellae in shape, and that of α-form obtained from solution in water-formic acid are parallelogramic. Electron diffraction study shows that chain packings in single crystals of two crystalline forms are very similar to those of nylon 6, respectively