Management of chronic diabetic foot skin ulcers require multidisciplinary approaches including diabetic control, wound care, antibiotic, shoe wear off-loading, and surgery in selected cases. The results are inconsistent and irregular, and most studies reported unsatisfactory results. Many adjunctive therapies are implemented in the care of chronic diabetic foot ulcers including hyperbaric oxygen therapy (HBO), ultrasound, recombinant human platelet-derived growth factor-BB (rPDGF-BB), vacuum assisted wound closure (VAWC) and acellular matrix. HBO is the most commonly utilized at the investigators institution. Mixed results of HBO in chronic diabetic foot ulcers are reported. Several studies reported that the beneficial effects of HBO, but none showed universal success. Therefore, the development of a new effective method of treatment for chronic diabetic ulcers is extremely valuable. Extracorporeal shockwave therapy (ESWT) acts as mechanotransduction that produces the therapeutic benefits through complex biological pathways including neovascularization and tissue regeneration. ESWT also showed bacteriostatic effects in experiments. Some studies reported the effectiveness of ESWT in acute and chronic soft tissue wounds. Others reported effectiveness of ESWT in chronic ulcers with 50% completely healed with 6 sessions of treatment. With this background, it appears that ESWT may be effective in the treatment of chronic diabetic foot ulcers. The purpose of this study is to evaluate the efficacy of ESWT in chronic foot ulcers, and to compared with that treated with HBO, and to study the molecular and blood flow perfusion before and after ESWT.