OBJECTIVE Glaucoma is an optic neuropathy in which optic nerve changes are important in diagnosis and progression, because the visual field may remain normal even while the optic nerve is undergoing significant damage. Accurate methods to objectively document the appearance of the optic nerve are necessary. In order for an optic disc imaging system to be clinically useful for detecting change, its reproducibility must be established. METHODS We measured the reproducibility of duplicate measurements in 59 eyes of 31 consecutive patients, grouped into glaucoma subjects (n = 29) and eyes with glaucoma (n = 30), with the 3.10 OIS Glaucoma-Scope. In order to simulate two visits on one day, sets of three optic disc images were obtained first, followed by a repeat set, and the best disc images of each (chosen by the computer) were compared. RESULTS The coefficients of variation of duplicate measurements for glaucoma suspects and patients with glaucoma were respectively: vertical cup/disc (c/d) ratio, 6.3% and 3.47%; horizontal c/d ratio, 4.61% and 2.97%; c/d area, 3.29% and 1.37%; cup area, 1.82% and 1.72%; mean position (MP) disc, 13.3% and 10.42%; MP total, 10.1% and 13.2%. For three eyes the examination was not possible (opacification of posterior capsule, miosis). CONCLUSIONS These results suggest that the 3.10 version of the OIS Glaucoma-Scope allows reproducible measurements in living eyes.