A 45 year old male officer was admitted due to upper substernal pain for 1 month, which was aggravated by swallowing. On past and family history, there was no specific history except heavy drinking. Simple chest x-ray revealed no specific abnormal findings. Preoperative esophagofiberscopy and Barium study showed midesophageal diverticulum, pulsion type, at about 2 cm below the left main bronchus. The opening of the diverticulum was located at the left posterolateral aspect of esophagus. Midesophageal false diverticulum, measuring 2 x 2 x 1 .S cm in size, was noted at about 5 cm under the aortic arch protruding through a slit-like muscular defect. After inversion of diverticular sac, interrupted sutures with 3-0 silks were done on muscular defect site, and mediastinal pleura was reinforced on the lesion with interrupted sutures. On 4th postoperative day, esophagography revealed no diverticulum or stenosis. Also esophagofiberscopy showed smooth mucosal tag without disturbance of passage. On 14th postoperative day, the patient was discharged uneventfully, and follow-up for 3 months after discharge revealed nothing abnormal symptoms. The authors report one case of midesophageal, pulsion type, false diverticulum. [KTCS 1982;4:447-450]