Purpose: To evaluate correlation between the clinical results and causative bacteria in diabetic foot patients with lower extremity amputation. Materials and Methods: One hundred twenty nine patients(131 feet) of diabetic foot amputations were followed for more than one year. Wound cultures were done by deep tissue or bone debris at first visit to our clinics. Retrospective analysis was performed using chart review and interview with the patients. Depending on the culture result, level of amputation, reinfection, duration of treatment, death rate, patient satisfaction and admission dates were evaluated. Results: Microorganisms were confirmed in 114 cases. In the other 17 cases, there were no cultured microorganisms. In bacterial growth group, Methicillin-sensitive Staphylococcus aureus was the most common pathogen and accounted for 34 cases. As other common pathogens, there were Methicillin-resistant Staphylococcus aureus(24 cases) and mixed infection(14 cases). Mortality is no difference in each infected group. Mixed bacterial infected patients have higher reinfection, longer hospital day and duration of treatment, but there is no difference in patients satisfaction and pain at last follow up. Conclusion: The most common pathogen in diabetic foot patients with lower extremity amputation was Methicillin-sensitive Staphylococcus aureus, and mixed bacterial infected patients have higher reinfection rate, longer admission date and duration of treatment than other bacterial infected patients.