This article reports the results of a forensic medical expertise of the gunshot wound in a serviceman wearing a bulletproof vest with special reference to the behaviour of the bullet that underwent deformation upon hitting the jacket. The authors emphasize the difficulty of differential diagnostics between the entry and exit wounds in the cases like that described in the paper. A series of experiments provided the data suggesting the specific mechanism by which exit gunshot wounds are formed in those parts of the body that adjoin the material from which the bulletproof vest is made. Special attention is given to the morphological features of such wounds and injuries to the biological tissues.