Baseline thyroxine, thyrotropin (TSH), and triiodothyronine (T3) resin uptake levels were measured in patients classified according to their topical intraocular response to corticosteroids. Results of thyroid studies were similar in patients with primary open-angle glaucoma and noncorticosteroid responsive (NN, intraocular pressure less than 20 mmHg after six weeks of topical 0.1% dexamethasone eyedrops) subjects. Primary open-angle glaucoma was not associated with the increased prevalence of low thyroid function values. The TSH suppression induced by oral dexamethasone was similar in NN subjects and patients with primary open-angle glaucoma. Patients with primary open-angle glaucoma did not demonstrate an increased glucocorticoid sensitivity as related to thyroid function. Thus, the adenohypophysial thyrotropic cell, the major site of dexamethasone inhibition of TSH secretion, does not appear to share the enhanced corticosteroid sensitivity of the eye, the hypothalamus, and the lymphocyte in patients with primary open-angle glaucoma.