OBJECTIVE To compare the posture-induced intraocular pressure (IOP) changes in eyes with open-angle glaucoma (OAG), primary angle closure (PAC) with or without glaucoma medications, and healthy control eyes with normal IOPs. METHODS The IOP was measured in the sitting position (SP) and the lateral decubitus position (LDP) with a rebound tonometer. The IOP in the LDP was measured in the upper eyes 5 minutes after assuming this posture. RESULTS Fifty-two patients with OAG, 52 with PAC, and 52 controls with normal IOPs were studied. The IOP in the SP measured with the rebound tonometer was 14.3 ± 4.0 mm Hg in eyes with OAG, 15.8 ± 4.5 mm Hg in eyes with PAC, and 13.9 ± 3.7 mm Hg in eyes with normal IOPs. None of these differences was significant (P = 0.060; ANOVA). The IOP in the LDP was significantly increased to 18.3 ± 4.6 mm Hg in eyes with OAG, 19.3 ± 4.4 mm Hg in eyes with PAC, and 17.3 ± 3.5 mm Hg in eyes with normal IOPs (P = 0.000 for all; paired t-tests). The postural IOP difference was +4.0 ± 2.2 mm Hg in OAG eyes, +3.5 ± 2.2 mm Hg in PAC eyes, and +3.4 ± 1.8 mm Hg in normal eyes, and these increases were not significantly different among the three groups (P = 0.309; ANOVA). The correlation between the posture-induced IOP changes and the axial length was not significant in each group. CONCLUSIONS Postural IOP changes are comparable among eyes with OAG, PAC with and without glaucoma medications, and control eyes.