The atypical mycobacteria have been reported with increasing frequency as a cause of human disease, but they have not received attention in the literature as a cause of ocular pathology. Their detection and evaluation pose a difficult problem. Differentiation of the various species from each other and from tuberculosis cannot be accomplished on clinical, radiologic, or histologic grounds. The criterion of virulence in laboratory animals cannot be used alone. Refined bacteriologic techniques are necessary.1,2 This presentation will not dwell on the specific morphology, cultural behavior, and biochemical characteristics used to classify and identify the atypical mycobacteria. The purpose of this paper is to report a corneal ulcer in which acid-fast bacilli were demonstrated in histologic sections of the cornea, and in which one of the atypical mycobacteria was implicated. Report of Case A 23-year-old white male was first seen at Duke Hospital on June 3, 1964. On Dec 13,