Little attention has been paid to the influence of orally administered antihypertensive drugs on intraocular pressure (IOP). Therefore, we evaluated the effects of oral medications on the IOPs and visual fields of 70 patients with systemic hypertension who had no ocular symptoms and had not visited any eye hospital. In patients with systemic hypertension treated with medication, the IOP value (mean, 18.3 +/- 4.2 mmHg; age range, 63.3 +/- 11.6 years) was significantly higher than in a control group with a similar age range who were not receiving oral medication (mean, 13.7 +/- 2.0 mmHg; age range, 62.5 +/- 7.8 years). In the group in which hypertension was controlled by medication, the IOPs were lower when orally administered beta-adrenergic blockers were given than in those patients with uncontrolled hypertension. In the group to whom calcium-channel blockers were administered orally, the IOPs were not lower. Angiotensin-converting enzyme inhibitors made the visual fields worse. This study suggests a modulating influence of orally administered drugs on the IOP and visual fields, which may be affected by whether or not the patient's blood pressure is controlled.