ABSTRACT.Purpose: To describe findings of spectral domain optical coherence tomography (SD-OCT) in the diagnosis of occult macular dystrophy (OMD). Materials and Methods: Five visually disturbed patients who had shown normal findings in full field electroretinogram (ERG), fundus photography and fluorescein angiography but abnormal findings in multifocal ERG had undergone SD-OCT. The morphologic changes in retina and macular thickness were detected and imaged by SD-OCT. We analysed the results of SD-OCT including macular thickness, inner segment and outer segment (IS ⁄ OS) boundary and external limiting membrane (ELM). Results: Mean age was 41.6 (22-63) in three male and two female patients in this study. Mean central foveal thickness was 142.9 (76-161) lm. All patients had shown decreased bowing of IS ⁄ OS boundary, and five of nine eyes were noted with disrupted IS ⁄ OS boundary of the photoreceptors according to SD-OCT. The interruption of external limiting membrane was noted in three of nine eyes. Conclusions: Spectral domain optical coherence tomography findings are useful in diagnosing OMD. Morphologic changes of the retina including deformity of the OS ⁄ IS boundary of the photoreceptors, disruption of the ELM and decreased foveal thickness may be important characteristics to consider when determining the pathophysiology and diagnosing criteria of OMD.