Pneumoperitoneum often occurs following a visceral perforation and is usually seen with peritonitis, requiring urgent surgical intervention. Non-surgical spontaneous pneumoperitoneum (not associated with organ perforation) is a rare situation caused by intrathoracic, intra-abdominal, gynaecologic, iatrogenic, and other reasons, and may be treated conservatively. Spontaneous idiopathic pneumoperitoneum is seen much less often than visceral perforation or other reasons causing intraabdominal gas. We present a case of idiopathic spontaneous pneumoperitoneum. A 75-year-old female patient applied with acute abdominal pain, subfebrile fever and nausea. Abdominal findings were not definitive, there was no leucocytosis but free intraabdominal air on the abdominal X-ray. The patient was observed for one day without oral feeding, nasogastric tubing, prophylactic antibiotics and saline infusion. At the first day of follow up she had only generalized abdominal pain on deep palpation, without other acute abdominal signs. She had mild leucosytosis, neutrophilia, and pneumoperitoneum on direct abdominal X-ray. On abdominal computerized tomography there was no pathologic sign other than intraabdominal free air and minimal free fluid in Douglas pouch. There was only a cholecystectomy (10 years ago) in her history, no chronic illness or other situation such as drug abuse, smoking or alcohol consumption. An emergency laparotomy was performed. Although no abdominal pathology could be found and the etiology could not be determined, the patient was discharged on the 5th postoperative day. Good patient history, appropriate laboratory tests, and radiologic tests combined with physical examination should be combined to avoid unnecessary laparotomy on non-surgical pneumoperitoneum, and minimally invasive techniques should also be considered.