Although home tonometry has been advocated in the management and diagnosis of glaucoma, the lack of proper instrumentation has precluded its routine performance. We have developed a self-tonometer that can be used by the patient at home and at work and have evaluated the performance of the instrument under these conditions. The results show that reproducibility of self-tonometer measurements is +/- 1.4 mm Hg and is independent of the user. When the readings of the self-tonometer in a given individual were compared with those of the Goldmann tonometer, they varied by +/- 2.4 mm Hg. Patients who could be trained in the clinic performed well and safely on their own. An average of fewer than five attempts was necessary to obtain four readings at each time of day. Our preliminary findings obtained during home tonometry demonstrated some of the benefits of repeated diurnal curves.