With acupuncture treatment becoming an increasingly popular analgesic, there have been increasing reports on its associated complications. Although pneumothorax is the most frequently reported injury caused by acupuncture needles, infectious complications may not be uncommon. Most infectious complications show less serious clinical manifestations than pneumothorax, but retroperitoneal or intraabdominal abscess caused by acupuncture may be much more serious conditions. We experienced a 56-yr-old male diabetic patient presenting with serious retroperitoneal abscess after acupuncture treatments. Emergency operative drainage with adequate antibiotic therapy was performed. Bacterial culture of blood and closed pus specimens recovered Klebsiella pneumoniae. In addition to application of better knowledge on anatomy, appropriate antiseptic practice by practitioners will reduce many serious complications associated with acupuncture.