PURPOSE: Diabetic foot ulcer is one of the most important diabetic complications because it increases the risk of amputations. Moreover, it lowers the quality of patients' life and increases the social medical expenses. Authors analyzed risk factors of intractable diabetic foot ulcer using retrospective study. MATERIALS AND METHODS: From January 2007 to December 2010, 40 patients who could not achieve complete healing despite more than 12 weeks of proper management among who had been diagnosed and treated as diabetic foot ulcer at our hospital were included and evaluated retrospectively. We compared the risk factors between two groups who were finally treated by amputation and non-amputation. RESULTS: The sample was composed of 31 male patients (77.5%) and 9 female patients (22.5%). Comorbidity including hypertension and hyperlipidemia were 77.5% and 80% each. By Wagner classification, 30 patients (80%) had ulcerative lesion over the grade 3. From bacteriology results, 29 patients (72.5%) had polybacteria infection. 35 patients (87.5%) had neuropathy and 26 patients (65%) had vascular stenosis at least one level. The mean initial ankle-brachial index and toe-brachial index were 0.982 and 0.439. In comparison between amputation group and non-amputation group, ulcer severity, number of stenotic vessel and initial ankle-brachial index/toe-brachial index had statistical significance. CONCLUSION: The most commonly risk factor of intractable diabetic foot ulcer was peripheral neuropathy reaching 87.5% of cases. In comparison with non-amputation group, ulcer severity according to Wagner classification, number of stenotic vessel and initial ankle-brachial index/toe-brachial index were demonstrated as a risk factor of amputation in intractable diabetic foot ulcer.