A 69-year-old male was admitted because of constipation and abdominal distension. A colon fiberscopic examination revealed the formation of ulceration. The trophozite of Entamoeba histolytica was detected from the specimens of colon mucosal biopsy of the ulcer. The stool was positive for the cysts of E. histolytica too. He had been in China and Southeast Asia during World War II. He returned home and experienced amoebic dysentry, and was treated with Emethin hydrochlolide. He suffered from amoebic disentry in 1970 and was treated with Emethine hydrochrolide again. After the War he had not gone abroad, and was not a homosexual. So this case was considered a latent infection of E. histolytica from the War. This time he was treated with metronidazol and minocycline. After the therapy, cysts were negative in the stool and the ulcer was cured on the colon fiberscopic examination.
