After a brief review of portable firearms or small caliber guns, the authors discuss various concepts concerning wound ballistics. Kinetic energy plays an important part in the damaging action of bullets, while the concepts of "shock wave" and "stopping power" have been supereded by the definition of wound profiles. These profiles are characteristic of each bullet. Clinically, they take the form of a temporary cavitation zone and a permanent cavity. The reaction of tissues crossed by the bullet largely depend on the elasticity of these tissues and the presence of bone. The concept of high velocity bullets should be abandoned. The phenomenon of cavitation alone and its dramatic clinical consequences should be taken into account and must guide the therapeutic approach.