BACKGROUND Hartmann procedure can be necessary for the treatment of rectal cancer and colonic perforation. The distal diverted intestinal tract is usually disregarded, while the proximal colon is diverted with a stoma. Most of the reported complications related to a diverted intestinal tract following Hartmann procedure include inflammation and intestinal tumors; however, there are only a few reports about postoperative anal complications. Herein, we report a rare case of anal atresia following Hartmann procedure. Anal atresia is generally considered as a congenital malformation; therefore, this was an extremely rare case, as there are no previous reports about anal atresia following Hartmann procedure. CASE REPORT An 84-year-old woman presented to our hospital with a persistent feeling of incomplete evacuation. She had undergone Hartmann procedure for diverticular disease of the sigmoid colon, with perforation, 5 years ago and had no major complications after the surgery. She had no history of anal disorders such as hemorrhoids or anal fissures. On examination, her anus was found to be closed by a thin skin, and computed tomography revealed stool retention in the diverted rectum. The anus was surgically opened to remove the stool, after which the feeling of incomplete evacuation resolved with no subsequent recurrence. CONCLUSIONS This is the first report of anal atresia in a patient following Hartmann procedure. The surgical intervention was effective in resolving the blockage and relieving the patient's feeling of incomplete evacuation.