The technique of cross‐sectional transmission electron microscopy has been used to investigate the defect content of epitaxial CdTe layers grown on {100} and {111}BGaAs and on {111}BCdTe by metalorganic chemical vapor deposition. Growth on {111} oriented substrates invaribly gave rise to layers of {111} orientation and these contained a large number of thin (100–1000 A˚) lamella twins lying parallel to the interface. In contrast, layers grown on {100} GaAs substrates were found to exhibit either {100} or {111} orientation. Epilayers with the former alignment contained arrays of misfit dislocations at the interface, whereas those with the latter orientation exhibited a density and distribution of lamella twins which were comparable with those of layers grown on {111} substrates. The presence of these defects in homoepitaxially grown CdTe, where the effects of lattice mismatch do not arise, clearly indicates that twinning in {111}BCdTe epilayers is a growth phenomenon.