To evaluate the change in intraocular pressure (IOP) after pharmacologic dilation in eyes with primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and eyes of normal subjects. This cross-sectional study was conducted in a university hospital-based setting. Patients with PXG, POAG, and normal subjects were consecutively selected and included in the study. Of the 125 eyes of 125 subjects; 46 (25 female) had PXG, 42 (29 female) had POAG, and 37 (20 female) belonged to the control group. Pharmacologic dilation procedure consisted of instillation of topical phenylephrine HCL 10 % followed 5 min by tropicamide 1 %. Studied variables were pre- and post-dilation IOP and also baseline measurements of anterior chamber angle, central corneal thickness, and pupillary diameter by Pentacam HR (Oculus, Wetzlar, Germany). Clinically significant IOP change was defined as a change of a parts per thousand yen2 mmHg from baseline. Randomly selected single eye of each patient was included in the analysis. The mean pre:post-dilation IOP of eyes with PXG and POAG was 17.39 +/- A 3.89:17.54 +/- A 3.98 and 15.92 +/- A 2.37:16.07 +/- A 2.89 mmHg, respectively. The difference between the pre- and post-dilation IOP of eyes with PXG and POAG was not statistically significant. The eyes of control subjects, however, had a statistically significant reduction of IOP from 14.24 +/- A 2.88 to 13.54 +/- A 2.94 mmHg (P = 0.005). 28.3 % (13/46) of eyes with PXG, 16.7 % (7/42) of eyes with POAG, and 2.7 % (1/37) of control eyes showed a clinically significant IOP elevation from baseline after the dilation. In this study, glaucoma patients proportionally experienced a higher rate of clinically significant IOP elevation after pupillary dilation, when compared to normal subjects.