Introduction: Diabetes mellitus can cause various complications, including diabetic foot ulcers (DFU). Vitamin D levels are known to be correlated with wound healing and insulin resistance. Method: This cross-sectional study aimed to determine the correlation between the serum level of vitamin D and the severity degree of DFU. Thirty DFU patients with normal ankle- brachial index, grouped into degrees according to the Wagner classification, were included in this study. Their serum level of vitamin D was examined using the chemiluminescent immunoassay method. The correlation between these two variables was analyzed. Results: Patients were 18 males (60%) and 12 females (40%) with an average age of 57 years. The average serum level of vitamin D was 10.58 ng/mL. A significant correlation was found between the serum level of vitamin D and the severity of DFU (r= -0.901, p <0.001).