OBJECTIVE To investigate diurnal intraocular pressure (IOP) fluctuation in eyes with angle-closure. METHODS Seventy-seven eyes of 77 newly diagnosed patients with angle closure [33 subjects with primary angle-closure suspects (PACS), 23 subjects with primary angle-closure (PAC), and 21 subjects with primary angle-closure glau-coma (PACG)] were enrolled after laser peripheral iridotomy for this prospective, cross-sectional study. Goldmann applanation tonometry (GAT) was performed at 08:00, 12:00, 16:00, 20:00, and 04:00 hours. Mean diurnal IOP, peak IOP, trough IOP, and IOP fluctuation (peak-trough) were compared between groups. RESULTS The mean age of the enrolled subjects was 56.8 ± 5.4 years, with 30 males and 47 females. Intraocular pressure fluctuation was significantly higher in the PACG (7.4 ± 2.8 mm Hg) and PAC (5.5 ± 2.3 mm Hg) groups compared with PACS subjects (4.4 ± 1.5 mm Hg). The highest IOP was recorded at 04:00 hours in all but two patients. Two PACS, 10 PAC and 8 PACG patients, with normal office hour IOP had IOP peaks > 21 mm Hg at night. Twenty-five percent patients (20/77) had abnormal IOP despite good office hour readings. CONCLUSIONS Primary angle-closure glaucoma and PAC eyes showed diurnal IOP fluctuations greater than 5 mm Hg in most subjects, with peak IOP recorded at 04:00 hours. Peak IOP was higher than office hour IOP recordings in subjects with angle-closure. A diurnal variation curve is recommended in these subjects, especially in cases with controlled IOP during office hours. How to cite this article: Bhartiya S, Ichhpujani P. Diurnal Intraocular Pressure Fluctuation in Eyes with Angle-closure. J Curr Glaucoma Pract 2015;9(1):20-23.