Subcutaneous emphysema affecting a limb in isolation is rare. Three cases of subcutaneous emphysema caused by a sucking wound of the limb are presented. Differentiation from infection with a gas-forming organism is imperative. This distinction can be made if a number of factors are taken into consideration. These include, concise knowledge of the history and mechanism of injury, and in particular, full appreciation of the amount of energy transfer causing the wound, the macroscopic appearance of the wound, the presence or absence of systemic symptoms, the time from injury to the development of subcutaneous emphysema, and the radiographic appearance of the soft tissues.