An investigation, using electron diffraction and high-resolution electron microscopy, on rapidly solidified Al-Cu–Mg alloy is reported. The splitting and the misalignment of diffraction spots are explained in terms of the coexistence of microcrystalline and micro-quasicrystalline grains, as confirmed by high-resolution electron microscopy. Diffuse scattering is mainly caused by secondary scattering between the two kinds of grain. The relationship between the structure of the rapidly solidified alloy and the structure of the crystalline phase (Al, Cu, Zn)49Mg32is discussed. An intermediate state between the crystalline and quasicrystalline states should be considered when regions larger than ∼ 10 Å are involved.