Convergent-beam electron diffraction zone-axis patterns have been obtained from transverse basal stacking faults in graphite and molybdenite. These patterns show a reduced symmetry and split reflections. The splitting and unsplitting of the reflections correspond to the visibility and invisibility of the stacking faults in the theory of diffraction contrast of imperfect crystals. This analysis can be extended to zone-axis patterns obtained from other crystal defects.