This chapter discusses various aspects of firearm injuries that can be caused by rifled weapons or smooth bore weapons. Injury caused by firearm is recognized by the appearance of clothing, entry and exit wounds, track of bullet and presence of bullet or pellets and residual matter in the clothing or around the entry wound and in tissues. Wad is found in the wound caused due to shotgun and this may prove to be an important clue to the type of cartridge used. As distance increases in mid/near range of shotgun, the main entrance wound progressively becomes smaller and individual pellet wounds increases in number. There is little or no evidence of burning, singeing, blackening and tattooing in case of rifled firearms wounds. Entry wound is usually circular in shape, smaller than the bullet, because of elasticity of skin, and associated with the usual zone of abraded collar, lacerated, inverted skin margins and a bigger dirt collar.