We retrospectively analyzed the therapeutic prognosis of primary open-angle glaucoma by the life-table method and the proportional hazards model. One hundred and eight patients (202 eyes) were studied. The follow-up period ranged from 6 to 125 months (40 +/- 25 months: mean +/- SD). The Kaplan-Meier life-table method indicated that therapeutic prognosis was significantly related to pretreatment intraocular pressure (IOP) and visual field defect, and that more intensive treatment was needed for higher IOP and more deteriorated visual field defect. Analysis by the proportional hazards model showed that pretreatment IOP and mean deviation (MD) measured by static perimetry were significant prognostic factors for non-surgical treatment and that the hazard ratios were 1.29-1.31 for a 5 mmHg rise in IOP and 1.44-1.83 for a 10 dB fall in MD. We concluded that the therapeutic prognosis of primary open-angle glaucoma is highly related to the level of IOP and the severity of visual field defect at the time of diagnosis.