This study was conducted with aims at evaluating the drug resistant characteristics of bacteria at infectious diabetic foot ulcers in patients at Cho Ray hospital from 2010 October to 2011 June. This was a prospective and cross section descriptive study. The results showed that proportion of used-antibiotics patients was high, accounting for 82 percent cases. The average amount of HbA1c in the patients was 11.00 + or - 3.79 percent. An average of 1.24 + or - 0.43 bacterial species per patient was isolated. Gram-negative aerobes were most frequently isolated (56.55 percent), followed by Gram-positive aerobes (43.45 percent). The bacteria became resistant to antibiotic, especially E. coli and Staphylococcus sp. Most patients controlled the glycemia poorly, not obeyed the treatment The infectious diabetic foot ulcers were often deep and had been used antibiotics on them before. Gram-negative aerobes prevailed more than Gram-positive ones at the ulcers. The percentage of antibioticresistant species increased over time.