The pathology of optic nerve in 80 diabetic subjects has been investigated in a morphologic study performed on autoptic material. Gliosis and demyelination resulted as the most frequently observed lesions (respectively 19 and 18 cases) and were associated to long history of diabetes. Additional findings were focal infarctions, atrophy, and broad spectrum of vascular lesions, mostly affecting the microcirculation, including thickening, hyalinosis, microaneurysms, as well as thromboses. An age-sex-matched control group, made of non diabetic subjects, did not share significantly lesions with the diabetics. Therefore, the authors suggest that diabetes mellitus plays an important role in the development of pathological changes in the optic nerves, thus claiming the marked vascular damage of early age onset diabetes as a possible pathogenetic factor.