OBJECTIVE There are two choices for the stabilization of penetrating lower extremity fractures in the forward surgical environment: bivalved circular casting and external fixation. The material and equipment requirements of these methods are of paramount importance in the austere forward surgical environment. METHODS Casualties from the Battle of the Black Sea in Somalia 1993 were examined. Penetrating lower extremity fractures requiring immobilization were identified. The relative packing volume and weight for each method of immobilization were analyzed. Finally, the current literature concerning the treatment of penetrating lower extremity fractures sustained in combat was reviewed. RESULTS The consumable material requirements of cast immobilization are 22.9 times greater by weight and 3.16 times greater by packing volume. Cast immobilization also has a greater durable equipment requirement. External fixation has multiple clinical advantages but is considerably more expensive. CONCLUSION Based on these variables, the authors determined that external fixation is the treatment of choice for penetrating lower extremity fractures in the forward surgical environment.