PURPOSE: To evaluate the availability of the mangled extremity severity score(MESS) in deciding the early treatment modality for the patients with open lower extremity fractures and severe soft tissue injury. MATERIALS AND METHODS: Analyzed 27 patients for the lower extremity open fractures with extensive soft tissue injury. A comparative study using a MESS, a cause of injury, vascular injury and a fracture pattern, average hospital stay and average hospital charges were analyzed, and daily living ability and subjective self-evaluation were assessed. RESULTS: There was statistically significant correlation applying MESS to patient group that had been operated by early amputation because of severe soft tissue and vascular injury. But there was no significant difference in the subjective self-assessment score, admission period and total cost during admission between each treatment method. CONCLUSION: MESS can be used as an objective assessment criteria in deciding the proper treatment modality for the cases of lower limbs fracture with extensive soft tissues and vascular injury.