Pneumoretroperitoneum is a rare event. It can be associated with infection, trauma, and medical interventions such as endoscopic procedures. Acupuncture is generally regarded as a safe procedure, yet cases of iatrogenic complications related with acupuncture have been reported. This report describes a case of pneumoretroperitoneum that developed after acupuncture. A 25-year-old female patient had been treated with acupuncture for her low back pain. Fever and right flank pain developed thereafter. Abdominal plain radiography and computed tomography (CT) disclosed retroperitoneal air along the right psoas muscle. After treatment with antibiotics and analgesics for a week, she was transferred to our hospital. The pneumoretroperitoneum disappeared on the follow-up abdominal CT. This is the first report of pneumoretroperitoneum following acupuncture.