A 42-year-old woman who developed a corneal ulcer in the left eye after radial keratotomy. The acid-fast stain showed that numerous clusters of acid-fast bacilli and Mycobacterium smegmatis were isolated on the culture. To the best of our knowledge, this is the first documented case of Mycobacterium smegmatis keratitis in the world literature. The sensitivity test showed that this organism resistant to all the anti-tuberculous agents and antibiotics we test. An initial response to amikacin and kanamycin was found, but relapse of infiltrate was noted one month later. The regimen was therefore changed to a combination of amikacin with ofloxacin. This patient had a favorable response to the topical therapy with amikacin and ofloxacin.