Bright–feld and high-resolution transmission electron microscopy were used for nano-scale structural studies of defects induced by implantation of arsenic ions with 190 keV energy and 1014 cm–2 fuence in n and p-type Hg0.78Cd0.22Te flms grown by molecular-beam epitaxy. A similarity in defect pattern formed by arsenic implantation in n and p-type material was observed. The electrical properties of the implanted layers in n and p-type flms also appeared to be similar, confrming the results of microscopic observations.