We report a series of 13 cases of atypical mycobacterial keratitis encountered in 1986 and 1987. The ratio of mycobacterial keratitis to the total number of corneal ulcer cases increased recently from 1% in 1984 to 8% in 1988 at our clinic. The diagnosis was established by a positive acid-fast stain of smear and a Löwenstein-Jensen media culture. Of the 13 cases, 12 were diagnosed within one week after the first presentation. All cases had a history of corneal trauma; there was foreign body injury in 10 cases, pterygium surgery in 2 cases and penetrating keratoplasty in one case. The clinical pictures of mycobacterial keratitis mostly included anterior stromal infiltrate (100%), necrotic abscess (69.2%), migration lesion (69.2%) and Descemet's folding (61.5%), showing resemblances to fungal keratitis in their characteristics. Species identification showed 11 cases of Mycobacterium fortuitum and 2 cases of Mycobacterium chelonei. On the sensitivity test Rifampin (12 cases, mean 19 mm), Kanamycin (11 cases, mean 29 mm), Ethambutol (11 cases, mean 28 mm), Amikacin (11 cases, mean 19 mm), Netilmicin (9 cases, mean 20 mm) and Tobramycin (8 cases, mean 20 mm) were more effective. Ten of the 13 cases completely healed after treatment and remained quiet during the follow up period of more than one year. In the other 3 cases there was no follow up. We emphasize that the recognition of the clinical features of the corneal findings will facilitate an early diagnosis of this disease and is of essential importance for the salvage of the eye.