A group of 46 patients with ocular hypertension (initial pressure 22-30 mmHg) have been followed prospectively for 5-7.5 years, with special emphasis on optic disc changes. A stereophoto of the disc was taken at each consultation. So far, 24 patients have been put on anti-glaucoma therapy. A slight increase in disc cupping revealed by stereophoto was the first pathological finding in 19 patients. Only one patient developed a field defect without visible disc changes. Neither disc description, cup/disc ratio measurement nor disc drawing were accurate enough to disclose small changes in the cup size. Considerably more patients in the treatment group had a pressure rise of 5 mm or more and repeated intraocular pressures of 30 mm or more during the observation. Stereophotography of the optic disc was found to be a valuable method in the diagnosis of early glaucoma.