In diabetic patients, foot ulcer is a common problem which prevalence during life is about 25%. Infection occurs as a complication in almost 50% of cases, is associated with significant morbidity and a reduced quality of life and is sometimes the trigger leading to amputation. Ulcers and infections occur among patients with predisposing factors such as peripheral neuropathy and arterial insufficiency, and require a multi-disciplinary care system. The knowledge of the microbiology of diabetic foot infection is necessary for a wise use of empirical and targeted antibiotic therapy. This article will focus on the definition and diagnosis of diabetic foot infection, on the main aspects of its microbiology and antibiotic treatment.